Merge in upstream version 0.5.0 to Debian pkg

2025-06-09 21:59:44 -05:00
parent b33d2ace99 72fd974da1
commit d8b08b46fc
121 changed files with 59189 additions and 728 deletions
--- a/.github/workflows/build-debian-package.yml
+++ b/.github/workflows/build-debian-package.yml
@@ -23,7 +23,7 @@ jobs:

      - name: Build from sources
        run: |
-          make -C src -j4 PREFIX=/usr
+          make -C src -j$(nproc) PREFIX=/usr

      - name: Prepare package workspace
        run: |
@@ -34,7 +34,7 @@ jobs:
          cp src/alsa-scarlett-gui               ${{ github.workspace }}/deb-workspace/usr/bin/
          cp src/vu.b4.alsa-scarlett-gui.desktop ${{ github.workspace }}/deb-workspace/usr/share/applications/
          cp src/img/vu.b4.alsa-scarlett-gui.png ${{ github.workspace }}/deb-workspace/usr/share/icons/hicolor/256x256/apps/
-          cp -r *.md img demo                    ${{ github.workspace }}/deb-workspace/usr/share/doc/${{ env.APP_NAME }}-${{ env.APP_VERSION }}/
+          cp -r *.md demo docs img               ${{ github.workspace }}/deb-workspace/usr/share/doc/${{ env.APP_NAME }}-${{ env.APP_VERSION }}/

      - name: Build debian package
        uses: jiro4989/build-deb-action@v2
@@ -42,8 +42,9 @@ jobs:
          package: ${{ env.APP_NAME }}
          package_root: ${{ github.workspace }}/deb-workspace
          maintainer: geoffreybennett
+          depends: 'libgtk-4-1, libasound2, alsa-utils'
          version: ${{ env.APP_VERSION }}
-          desc: ${{ env.APP_NAME }} is a Gtk4 GUI for the ALSA controls presented by the Linux kernel Focusrite Scarlett Gen 2/3 Mixer Driver.
+          desc: ${{ env.APP_NAME }} is a Gtk4 GUI for the ALSA controls presented by the Linux kernel Focusrite USB drivers.

      - name: Upload Release Asset
        uses: actions/upload-release-asset@v1
--- a/.github/workflows/build-flatpak-package.yml
+++ b/.github/workflows/build-flatpak-package.yml
@@ -14,7 +14,7 @@ jobs:
    name: "Flatpak"
    runs-on: ubuntu-latest
    container:
-      image: bilelmoussaoui/flatpak-github-actions:gnome-45
+      image: bilelmoussaoui/flatpak-github-actions:gnome-47
      options: --privileged
    steps:
    - uses: actions/checkout@v4
--- a/FAQ.md
+++ b/FAQ.md
@@ -1,37 +1,40 @@
-# FAQ for the Scarlett2 Mixer Driver and `alsa-scarlett-gui`
+# FAQ for the ALSA Scarlett Control Panel (`alsa-scarlett-gui`)

 ## What is this?

-The Scarlett2 Protocol Driver (also known as the Scarlett2 Mixer
-Driver) is a part of the Linux kernel, enhancing the ALSA kernel
-driver with additional controls for Focusrite Scarlett, Clarett, and
-Vocaster interfaces.
+The ALSA Scarlett Control Panel (`alsa-scarlett-gui`) is an
+easy-to-use application for adjusting the ALSA controls provided by
+three Linux kernel drivers for Focusrite USB interfaces:
+
+1. The Scarlett 1st Gen Mixer Driver (for 1st Gen 6i6, 8i6, 18i6, 18i8, 18i20)
+2. The Scarlett2 Protocol Driver (for 2nd/3rd Gen interfaces, small 4th Gen, Clarett, and Vocaster)
+3. The FCP (Focusrite Control Protocol) Driver (for big 4th Gen interfaces: 16i16, 18i16, 18i20)

 To check if your kernel is already up-to-date, and how to upgrade if
 not, see the [Control Panel Installation Prerequisites — Linux
-Kernel](https://github.com/geoffreybennett/alsa-scarlett-gui/blob/master/INSTALL.md).
+Kernel](docs/INSTALL.md).

-`alsa-scarlett-gui` is an easy-to-use application to adjust those
-controls.
+## Do I need these drivers for my Focusrite interface?

-## Do I need the driver for my Focusrite interface?
-
-In order to get audio working? No. Focusrite USB interfaces are
+For basic audio functionality? No. Focusrite USB interfaces are
 “plug-and-play” — they are USB Audio Class Compliant, meaning they
 work out-of-the-box with the standard ALSA USB audio driver (to get
 full functionality on Scarlett 3rd/4th Gen/Vocaster interfaces, first
 deactivate MSD mode by holding down the 48V button while powering it
 on).

+However, to access the mixer, routing, and hardware-specific features,
+you'll need the appropriate driver for your interface model.
+
 ## MSD Mode?

-“MSD Mode” is the “Mass Storage Device Mode” that the Scarlett 3rd and
+"MSD Mode" is the "Mass Storage Device Mode" that the Scarlett 3rd and
 4th Gen interfaces ship in.

 If MSD Mode is enabled, you need to disable it and restart your
 interface to get access to its full functionality.

-When you plug the interface in, there’ll be a tiny read-only virtual
+When you plug the interface in, there'll be a tiny read-only virtual
 disk that has a link to the Focusrite product registration page; until
 you turn off MSD Mode not all features of the interface will be
 available.
@@ -40,49 +43,62 @@ You can turn off MSD Mode by holding down the 48V button while
 powering on the interface, or by clicking the button in
 `alsa-scarlett-gui` and rebooting it.

-## What is the purpose of the driver if it’s not needed for audio?
+If you do the recommended/required (depending on the model) firmware
+update, MSD Mode will automatically be turned off.

-This driver is for users who want more control over their interface.
-It allows for detailed manipulation of internal audio routing and
-settings specific to Scarlett, Clarett, and Vocaster devices, beyond
-the basic audio I/O functionality. Also, being able to monitor the
-audio levels seen by the interface is really useful.
+## What is the purpose of these drivers if they're not needed for basic audio?
+
+These drivers are for users who want more control over their
+interface. They allow for detailed manipulation of:
+
+- Internal audio routing
+- Hardware-specific settings
+- Mixer functionality
+- Level monitoring
+- Input/output configuration
+
+These controls go beyond the basic audio I/O functionality provided by
+the generic ALSA USB audio driver.

 ## What interfaces are supported?

- All Scarlett 2nd Gen interfaces with software controls (there are no
-  software controls on the 2nd Gen Solo and 2i2, so the mixer driver
-  is irrelevant).
+The ALSA Scarlett Control Panel supports:

- All Scarlett 3rd Gen interfaces.
+- **Scarlett 1st Gen**: 6i6, 8i6, 18i6, 18i8, 18i20
+- **Scarlett 2nd Gen**: 6i6, 18i8, 18i20
+- **Scarlett 3rd Gen**: Solo, 2i2, 4i4, 8i6, 18i8, 18i20
+- **Scarlett 4th Gen**: Solo, 2i2, 4i4, 16i16, 18i16, 18i20
+- **Clarett USB and Clarett+**: 2Pre, 4Pre, 8Pre
+- **Vocaster**: One, Two

- Scarlett 4th Gen Solo, 2i2, and 4i4.
-
- All Clarett USB and Clarett+ interfaces.
-
- Vocaster One and Vocaster Two.
+Note: The Scarlett 1st and 2nd Gen small interfaces (Solo, 2i2, 2i4)
+don't have any software controls. All the controls are available from
+the front panel, so they don't require the specialised drivers or this
+GUI.

 ## Where are the options to set the sample rate and buffer size?

-It’s important to note that the Scarlett2 driver and
-`alsa-scarlett-gui` have nothing to do with audio input/output to and
-from the device. This task is managed by the generic part of the ALSA
-USB soundcard driver.
+The ALSA Scarlett Control Panel doesn't handle audio input/output
+settings like sample rate and buffer size. These settings are managed
+by the application using the soundcard, typically a sound server such
+as PulseAudio, JACK, or PipeWire.

-Audio settings like the sample rate and buffer size are chosen by the
-application which is using the soundcard. In most cases, that is a
-sound server such as PulseAudio, JACK, or PipeWire.
+The sample rate shown in the control panel is informative only and
+displays the current rate being used by applications. If it shows
+“N/A” then no application is using the interface.

 Note that not all features are available at higher sample rates; refer
 to the user manual of your interface for more information.

 ## Help?!

-For help with the driver:
-https://github.com/geoffreybennett/scarlett-gen2/issues
+For help with the Scarlett2 and FCP kernel drivers:
+https://github.com/geoffreybennett/linux-fcp/issues
+
+For help with the FCP user-space side:
+https://github.com/geoffreybennett/fcp-support/issues

 For help with `alsa-scarlett-gui`:
 https://github.com/geoffreybennett/alsa-scarlett-gui/issues

-For general Linux audio help:
-https://linuxmusicians.com
+For general Linux audio help: https://linuxmusicians.com
--- a/2
+++ b/2
@@ -10,7 +10,7 @@ default:
 	@echo
 	@echo "If you want to build and install from source, please try:"
 	@echo "  cd src"
-	@echo "  make -j4"
+	@echo "  make -j$(shell nproc)"
 	@echo "  sudo make install"
 	@echo
 	@echo "This Makefile knows about packaging:"
--- a/README.md
+++ b/README.md
@@ -1,21 +1,26 @@
-# ALSA Scarlett2 Control Panel (`alsa-scarlett-gui`)
+# ALSA Scarlett Control Panel (`alsa-scarlett-gui`)

 `alsa-scarlett-gui` is a Gtk4 GUI for the ALSA controls presented by
-the Linux kernel Focusrite Scarlett2 USB Protocol Mixer Driver.
+the three Linux kernel Focusrite USB drivers:
+
+- Scarlett 1st Gen Driver for ALSA
+- Scarlett2 USB Protocol Mixer Driver
+- FCP (Focusrite Control Protocol) Driver

 Supported interfaces:
+- Scarlett 1st Gen 6i6, 8i6, 18i6, 18i8, 18i20
 - Scarlett 2nd Gen 6i6, 18i8, 18i20
 - Scarlett 3rd Gen Solo, 2i2, 4i4, 8i6, 18i8, 18i20
- Scarlett 4th Gen Solo, 2i2, 4i4
+- Scarlett 4th Gen Solo, 2i2, 4i4, 16i16, 18i16, 18i20
 - Clarett 2Pre, 4Pre, 8Pre USB
 - Clarett+ 2Pre, 4Pre, 8Pre
 - Vocaster One and Vocaster Two

 ## About

-<img src="src/img/alsa-scarlett-gui-logo.png" align="right">
+<img src="img/alsa-scarlett-gui.png" align="right">

-The Focusrite USB audio interfaces are class compliant meaning that
+All Focusrite USB audio interfaces are class compliant meaning that
 they work “out of the box” on Linux as audio and MIDI interfaces
 (although on Gen 3/4/Vocaster you need to disable MSD mode first for
 full functionality). However, except for some of the smallest models,
@@ -28,8 +33,8 @@ awful experience. The existing applications like `alsamixer` and
 controls presented for the Gen 3 18i20. Even the smallest Gen 3 4i4
 interface at last count had 84 ALSA controls.

-Announcing the ALSA Scarlett2 Control Panel, now supporting Scarlett
-Gen 2, 3, 4, Clarett, and Vocaster!
+Announcing the ALSA Scarlett Control Panel, now supporting all
+Scarlett Gen 1, 2, 3, 4, Clarett, and Vocaster USB interfaces!

 ![Demonstration](img/demo.gif)

@@ -43,12 +48,16 @@ known issues.

 Information specific to various models:

+- [Scarlett 1st Gen](docs/iface-1st-gen.md)
+
 - [Scarlett 3rd Gen Solo and 2i2](docs/iface-small.md)

 - [Scarlett 2nd Gen 6i6+, 3rd Gen 4i4+, Clarett USB, and
  Clarett+](docs/iface-large.md)

- [Scarlett 4th Gen](docs/iface-4th-gen.md)
+- [Scarlett Small 4th Gen](docs/iface-4th-gen-small.md)
+
+- [Scarlett Big 4th Gen](docs/iface-4th-gen-big.md)

 ## Donations

@@ -63,7 +72,7 @@ you! Any donation is appreciated.

 ## License

-Copyright 2022-2024 Geoffrey D. Bennett
+Copyright 2022-2025 Geoffrey D. Bennett

 This program is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
--- a/alsa-scarlett-gui.spec.template
+++ b/alsa-scarlett-gui.spec.template
@@ -1,4 +1,4 @@
-Summary: ALSA Scarlett Gen 2/3 Control Panel
+Summary: ALSA Scarlett Control Panel
 Name: alsa-scarlett-gui
 Version: VERSION
 Release: 1%{?dist}
@@ -9,22 +9,24 @@ Source: %{name}-%{version}.tar.gz
 %description

 alsa-scarlett-gui is a Gtk4 GUI for the ALSA controls presented by the
-Linux kernel Focusrite Scarlett Gen 2/3 Mixer Driver.
+Linux kernel Focusrite USB drivers.

 %prep
 %setup

 %build
-make -C src -j4 VERSION=%{version} PREFIX=/usr
+make -C src %{?_smp_mflags} VERSION=%{version} PREFIX=/usr

 %install
 %make_install -C src PREFIX=/usr
 DOCDIR=%{buildroot}/usr/share/doc/%{name}-%{version}
 mkdir -p $DOCDIR/img
 mkdir $DOCDIR/demo
+mkdir $DOCDIR/docs
 cp *.md $DOCDIR
 cp img/* $DOCDIR/img
 cp demo/* $DOCDIR/demo
+cp docs/* $DOCDIR/docs

 %files
 %doc /usr/share/doc/%{name}-%{version}
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/demo/Scarlett
+++ b/demo/Scarlett
--- a/docs/INSTALL.md
+++ b/docs/INSTALL.md
@@ -1,29 +1,46 @@
-# ALSA Scarlett2 Control Panel Installation
+# ALSA Scarlett Control Panel Installation

 ## Prerequisites

 ### Linux Kernel

-You need to be running a Linux Kernel that has the ALSA Scarlett2
-Protocol Driver. Use `uname -r` to check what kernel version you are
-running.
+You need to be running a Linux Kernel that contains the appropriate
+driver for your interface. Use `uname -r` to check what kernel version
+you are running.

- For reasonable functionality of Scarlett 2nd and 3rd Gen and Clarett
-  interfaces, you need at least Linux kernel version 6.7
- For Scarlett 4th Gen support and firmware updates from Linux, you
-  need at least 6.8
- For Vocaster support, you’ll need to build an updated
-  `snd-usb-audio` driver (or wait for 6.10)
+Check the following table to see which driver your interface uses and
+the first kernel version that the driver was included in:

-If you’ve got a Vocaster, or if your distribution doesn’t include a
-recent-enough kernel for your interface, you can get the latest driver
-from here and build it for your current kernel:
+| Series    | Models | Driver | Kernel Version |
+|-----------|--------|--------|:----------------------:|
+| Scarlett 1st Gen | Solo, 2i2, 2i4 | N/A* | Any |
+| Scarlett 1st Gen | 6i6, 8i6, 18i6, 18i8, 18i20 | Scarlett 1st Gen Mixer Driver | 3.19+ |
+| Scarlett 2nd Gen | Solo, 2i2, 2i4 | N/A* | Any |
+| Scarlett 2nd Gen | 6i6, 18i8, 18i20 | Scarlett2 Mixer Driver | 6.7+ |
+| Scarlett 3rd Gen | Solo, 2i2, 4i4, 8i6, 18i8, 18i20 | Scarlett2 Mixer Driver | 6.7+ |
+| Scarlett 4th Gen | Solo, 2i2, 4i4 | Scarlett2 Mixer Driver | 6.8+ |
+| Scarlett 4th Gen | 16i16, 18i16, 18i20 | FCP (Focusrite Control Protocol) Driver | 6.14+ |
+| Clarett USB and Clarett+ | 2Pre, 4Pre, 8Pre | Scarlett2 Mixer Driver | 6.7+ |
+| Vocaster | One, Two | Scarlett2 Mixer Driver | 6.10+ |

-https://github.com/geoffreybennett/scarlett-gen2/releases
+\* The small 1st Gen and 2nd Gen models don’t have any proprietary
+software controls so they don’t need a driver beyond the standard ALSA
+USB Audio driver. This means that this application (alsa-scarlett-gui)
+is not needed, useful, or supported for these models.

-#### Enabling the Driver
+If your distribution doesn’t include a recent-enough kernel for your
+interface, you can get the latest driver from here and build it for
+your current kernel if it's not too old (the Scarlett2 and FCP drivers
+are both maintained in the same tree here):
+https://github.com/geoffreybennett/linux-fcp/releases

-As of Linux 6.7 the driver is enabled by default. Check the driver
+Kernel 6.7 and later have the Scarlett2 driver enabled by default. The
+Scarlett 1st Gen driver and the FCP drivers are always enabled.
+
+#### Enabling the Scarlett2 Driver
+
+Some kernels before 6.7 have an earlier version of the Scarlett2
+driver which is disabled by default. If this is you, check the driver
 status (after plugging your interface in) with this command:

 ```
@@ -35,12 +52,12 @@ If all is good you’ll see messages like this:
 ```
 New USB device found, idVendor=1235, idProduct=8215, bcdDevice= 6.0b
 Product: Scarlett 18i20 USB
-Focusrite Scarlett Gen 3 Mixer Driver enabled (pid=0x8215); report
-any issues to https://github.com/geoffreybennett/scarlett-gen2/issues
+Focusrite Scarlett Gen 3 Mixer Driver enabled (pid=0x8215); ...
 ```

 If you don’t see the “Mixer Driver” message or if it shows “disabled”
-then check the [OLDKERNEL.md](OLDKERNEL.md) instructions.
+then check the [OLDKERNEL.md](OLDKERNEL.md) instructions (or,
+preferably, upgrade your distro/kernel!).

 ### Gtk4

@@ -49,16 +66,27 @@ doesn’t have them natively, try the Flatpak instructions below.

 ### Firmware

-As of Linux 6.8, firmware updates of all the supported interfaces can
-be done through Linux. This is mandatory for Scarlett 4th Gen and
-Vocaster interfaces (unless you’ve already updated it using the
-manufacturer’s software), and optional for Scarlett 2nd and 3rd Gen,
-Clarett USB, and Clarett+ interfaces.
+#### Scarlett2 Driver
+
+As of Linux 6.8, firmware updates of all supported interfaces from the
+2nd Gen onwards can be done through Linux. This is mandatory for
+Scarlett 4th Gen and Vocaster interfaces (unless you’ve already
+updated it using the manufacturer’s software), and optional but
+recommended for Scarlett 2nd and 3rd Gen, Clarett USB, and Clarett+
+interfaces.

 Download the firmware from
 https://github.com/geoffreybennett/scarlett2-firmware and place it in
 `/usr/lib/firmware/scarlett2` or use the RPM/deb package.

+#### FCP Driver
+
+Firmware updates for the big Scarlett 4th Gen interfaces is currently
+only possible through the CLI `fcp-tool` utility available in the
+[fcp-support](https://github.com/geoffreybennett/fcp-support). You
+need to install this package and update the firmware before
+alsa-scarlett-gui will work.
+
 ## Building and Running

 On Fedora, these packages need to be installed:
@@ -79,6 +107,12 @@ On Ubuntu:
 sudo apt -y install git make gcc libgtk-4-dev libasound2-dev libssl-dev
 ```

+On Arch:
+
+```
+sudo pacman -S gtk4
+```
+
 To download from github:

 ```
@@ -90,7 +124,7 @@ To build:

 ```
 cd src
-make -j4
+make -j$(nproc)
 ```

 To run:
--- a/docs/OLDKERNEL.md
+++ b/docs/OLDKERNEL.md
@@ -1,14 +1,18 @@
 # ALSA Scarlett2 Usage With Old Kernels

+**This information is mostly for historical purposes. If you’re
+running a kernel before 6.7, you should upgrade to a newer kernel.**
+
 Linux kernel 6.7 (check your version with `uname -r`) was the first
-kernel version with this driver enabled by default. It’s recommended
-that you run 6.7 or later, or build the backported driver for your
-kernel. If you do, then these instructions aren’t relevant; continue
-with [INSTALL.md](INSTALL.md) for prerequisites, how to build,
-install, and run `alsa-scarlett-gui`.
+kernel version with the Scarlett2 driver enabled by default. It’s
+recommended that you run 6.7 or later, or build the backported driver
+for your kernel. If you do, then these instructions aren’t relevant;
+continue with [INSTALL.md](INSTALL.md) for prerequisites, how to
+build, install, and run `alsa-scarlett-gui`.

 If you’ve got a Scarlett Gen 2 or 3 or a Clarett+ 8Pre and don’t mind
-the level meters not working, then the minimum kernel versions are:
+the level meters not working, then the first kernel support was added
+in:

 - **Scarlett Gen 2**: Linux 5.4 (bugs fixed in Linux 5.14)
 - **Scarlett Gen 3**: Linux 5.14
@@ -18,7 +22,7 @@ the level meters not working, then the minimum kernel versions are:

 Install the latest version of the backported driver from here:

-https://github.com/geoffreybennett/scarlett-gen2/releases
+https://github.com/geoffreybennett/linux-fcp/releases

 then you can ignore the instructions below.

--- a/docs/USAGE.md
+++ b/docs/USAGE.md
@@ -1,4 +1,4 @@
-# ALSA Scarlett2 Control Panel Usage
+# ALSA Scarlett Control Panel Usage

 Refer to [INSTALL.md](INSTALL.md) for prerequisites, how to build,
 install, and run.
@@ -59,7 +59,7 @@ restart the interface, and in a moment the main window will appear.
 The View → Startup menu option opens a window to configure settings
 that only take effect when the interface is powered on.

-The options common to all interfaces are:
+The options common to most interfaces are:

 - **Reset Configuration**: this will reset the configuration to the
  factory defaults. This is particularly useful with the 4th Gen and
@@ -105,9 +105,13 @@ menu option File → Interface Simulation to load.
 The controls and menu items which are available vary widely, depending
 on your specific interface.

-There are three broad categories of interfaces with different
+There are five broad categories of interfaces with different
 capabilities; each category of interface is described in a separate
-ocument:
+document:
+
+- [Scarlett 1st Gen 6i6+](iface-1st-gen.md)
+
+  Full routing and mixing capabilities, but some significant caveats.

 - [Scarlett 3rd Gen Solo and 2i2](iface-small.md)

@@ -119,13 +123,21 @@ ocument:

  Full routing and mixing capabilities.

- [Scarlett 4th Gen](iface-4th-gen.md)
+- [Scarlett Small 4th Gen](iface-4th-gen-small.md)

  Full routing and mixing capabilities, remote-controlled input gain,
  but no output controls.

+- [Scarlett Big 4th Gen](iface-4th-gen-big.md)
+
+  Full routing and mixing capabilities, remote-controlled input gain
+  and output volume controls.
+
 ## Known Bugs/Issues

+- For interfaces using the FCP driver, alsa-scarlett-gui needs to be
+  started after the interface is connected and fcp-server has started.
+
 - Load/Save uses `alsactl` which will be confused if the ALSA
  interface name (e.g. `USB`) changes.

--- a/docs/iface-1st-gen.md
+++ b/docs/iface-1st-gen.md
@@ -0,0 +1,160 @@
+# ALSA Scarlett Control Panel
+
+## Scarlett 1st Gen Interfaces
+
+This document describes how to use the ALSA Scarlett Control Panel
+with the Scarlett 1st Gen interfaces:
+
+- Scarlett 1st Gen 6i6, 8i6, 18i6, 18i8, 18i20
+
+Note: The 1st Gen Scarlett Solo, 2i2, and 2i4 have all their controls
+accessible from the front panel of the device, and there are no
+proprietary software controls, so they do not require this control
+panel software.
+
+## Important Driver Limitations
+
+The 1st Gen Scarlett devices have some important limitations in the
+ALSA driver implementation that you should be aware of:
+
+1. **Initial State Detection**: The driver cannot read the current
+   state of hardware controls (this appears to be a limitation of the
+   device firmware). When alsa-scarlett-gui starts, what you see will
+   not reflect the actual state of your device unless the controls
+   have previously been set since startup.
+
+2. **State Update Issues**: The driver only updates the hardware state
+   when it thinks a setting needs to be changed. If the driver
+   incorrectly believes a control is already in the desired state, it
+   won't actually update the control.
+
+3. **Level Meters**: The driver does not support reading the level
+   meters from the hardware.
+
+4. **Startup Controls**: The driver has no startup controls.
+
+### Recommended Workaround
+
+To ensure your settings are properly applied:
+
+1. Apply a "zero" configuration that sets all controls to values that
+   are *not* what you desire.
+2. Then apply your desired configuration
+
+This two-step process helps ensure that the driver actually sends all
+commands to the hardware. You may want to create a script using
+`alsactl` for this purpose.
+
+## Main Window
+
+The main window is divided into three sections:
+
+- Global Controls
+- Analogue Input Controls
+- Analogue Output Controls
+
+The particular controls available depend on the interface model.
+
+Note that the View menu option lets you open two other windows which
+contain additional controls, described in the following sections:
+- [Routing](#routing)
+- [Mixer](#mixer)
+
+The Levels and Startup windows that are available for later-generation
+interfaces are not available for 1st Gen interfaces due to driver limitations.
+
+### Global Controls
+
+Global controls relate to the operation of the interface as a whole.
+
+#### Clock Source
+
+Clock Source selects where the interface receives its digital clock
+from. If you aren't using S/PDIF or ADAT inputs, set this to Internal.
+
+#### Sync Status
+
+Sync Status indicates if the interface is locked to a valid digital
+clock. If you aren't using S/PDIF or ADAT inputs and the status is
+Unlocked, change the Clock Source to Internal.
+
+### Analogue Input Controls
+
+#### Inst
+
+The Inst buttons are used to select between Mic/Line and Instrument
+level/impedance. When plugging in microphones or line-level equipment
+(such as a synthesizer, external preamp, or effects processor) to the
+input, set it to “Line”. The “Inst” setting is for instruments with
+pickups such as guitars.
+
+#### Pad
+
+Enabling Pad engages a 10dB attenuator in the channel, giving you more
+headroom for very hot signals.
+
+#### Gain
+
+The Gain switch selects Low or High gain for the input channel.
+
+### Analogue Output Controls
+
+The analogue output controls let you set the output volume (gain) on
+the analogue line outputs.
+
+Click and drag up/down on the volume dial to change the volume, use
+your arrow keys, Home/End/PgUp/PgDn keys, or use your mouse scroll
+wheel to adjust. You can also double-click on it to quickly toggle the
+volume between off and 0dB.
+
+## Routing
+
+The routing window allows complete control of signal routing between
+the hardware inputs/outputs, internal mixer, and PCM (USB)
+inputs/outputs.
+
+![Routing Window](../img/scarlett-1st-gen-6i6-routing.png)
+
+To manage the routing connections:
+
+- Click and drag from a source to a sink or a sink to a source to
+  connect them. Audio from the source will then be sent to that sink.
+
+- Click on a source or a sink to clear the links connected to that
+  source/sink.
+
+Note that a sink can only be connected to one source, but one source
+can be connected to many sinks. If you want a sink to receive input
+from more than one source, use the mixer inputs and outputs:
+
+- Connect the sources that you want to mix together to mixer inputs
+- Connect mixer outputs to the sinks that you want to receive the
+  mixed audio
+- Use the Mixer window to set the amount of each mixer input that is
+  sent to each mixer output
+
+The Presets menu can be used to clear all connections, or to set up
+common configurations:
+
+- The "Direct" preset sets up the usual configuration using the
+  interface as a regular audio interface by connecting:
+
+  - all Hardware Inputs to PCM Inputs
+  - all PCM Outputs to Hardware Outputs
+
+- The "Preamp" preset connects all Hardware Inputs to Hardware
+  Outputs.
+
+- The "Stereo Out" preset connects PCM 1 and 2 Outputs to pairs of
+  Hardware Outputs.
+
+## Mixer
+
+If you use the Routing window to connect Sources to Mixer Inputs and
+Mixer Outputs to Sinks, then you can use the Mixer window to set the
+amount of each Mixer Input that is sent to each Mixer Output using a
+matrix of controls.
+
+Click and drag up/down on the gain controls to adjust, or use your
+mouse scroll wheel. You can also double-click on the control to
+quickly toggle between off and 0dB.
--- a/docs/iface-4th-gen-big.md
+++ b/docs/iface-4th-gen-big.md
@@ -0,0 +1,210 @@
+# ALSA Scarlett Control Panel
+
+## Scarlett Big 4th Gen Interfaces
+
+This document describes how to use the ALSA Scarlett Control Panel
+with the big Scarlett 4th Gen interfaces:
+
+- Scarlett 4th Gen 16i16, 18i16, 18i20
+
+### FCP Driver
+
+The big 4th Gen interfaces are supported by a new “FCP” (Focusrite
+Control Protocol) driver introduced in Linux 6.14. If you haven't
+installed
+[fcp-support](https://github.com/geoffreybennett/fcp-support) yet, you
+need to do that (and update the firmware) before you can use
+alsa-scarlett-gui.
+
+## Main Window
+
+The main window is divided into three sections:
+- Global Controls
+- Analogue Input Controls
+- Analogue Output Controls
+
+The main window for the 16i16 interface is shown below. The 18i16 and
+18i20 interfaces are similar, but with more controls.
+
+![Main Window](../img/iface-4th-gen-big.png)
+
+### Global Controls
+
+#### Clock Source (interfaces with S/PDIF or ADAT inputs only)
+
+Clock Source selects where the interface receives its digital clock
+from. If you aren’t using S/PDIF or ADAT inputs, set this to Internal.
+
+#### Sync Status
+
+Sync Status indicates if the interface is locked to a valid digital
+clock. If you aren’t using S/PDIF or ADAT inputs and the Sync Status
+is Unlocked, change the Clock Source to Internal.
+
+#### Sample Rate
+
+Sample Rate is informative only, and displays the current sample rate
+if the interface is currently in use. In ALSA, the sample rate is set
+by the application using the interface, which is usually a sound
+server such as PulseAudio, JACK, or PipeWire.
+
+#### Speaker Switching
+
+Speaker Switching lets you swap between two pairs of monitoring
+speakers very easily.
+
+### Analogue Input Controls
+
+#### Input Select
+
+The “Input Select” control allows you to choose which channel the
+hardware 48V, Inst, Air, Auto, and Safe buttons control.
+
+#### Link
+
+The “Link” control links the 48V, Inst, Air, Auto, and Safe controls
+together so that they control a stereo pair of channels
+simultaneously.
+
+#### Gain
+
+The “Gain” controls adjust the input gain for the selected channel.
+Click and drag up/down on the control to adjust the gain, use your
+mouse scroll wheel, or click the control to select it and use the
+arrow keys, Page Up, Page Down, Home, and End keys.
+
+#### Autogain
+
+When the “Autogain” control is enabled, the interface will listen to
+the input signal for ten seconds and automatically adjust the gain to
+get the best signal level. When autogain is not running, the
+most-recent autogain exit status is shown below the “Autogain”
+control.
+
+#### Safe
+
+“Safe” mode is a feature that automatically reduces the gain if the
+signal is too loud. This can be useful to prevent clipping.
+
+#### Instrument
+
+The Inst button(s) are used to select between Mic/Line and Instrument
+level/impedance. When plugging in microphones or line-level equipment
+(such as a synthesizer, external preamp, or effects processor) to the
+input, set it to “Line”. The “Inst” setting is for instruments with
+pickups such as guitars.
+
+#### Air
+
+The Scarlett 3rd Gen introduced Air mode which transformed your
+recordings and inspired you while making music by boosting the
+signal’s high-end. The 4th Gen interfaces now call that “Air Presence”
+and add a new mode “Air Presence+Drive” which boosts mid-range
+harmonics in your sound.
+
+#### Phantom Power (48V)
+
+Turning the “48V” switch on sends “Phantom Power” to the XLR
+microphone input. This is required for some microphones (such as
+condensor microphones), and damaging to some microphones (particularly
+vintage ribbon microphones).
+
+### Analogue Output Controls
+
+The analogue output controls are a bit sparse. More controls are
+coming soon.
+
+#### Volume Knobs
+
+The volume knobs control the volume of the analogue outputs. The two
+channels of the stereo pairs are shown separately, but are internally
+linked together.
+
+#### Mute and Dim
+
+The speaker icon buttons are “mute” and “dim” (reduce volume) buttons,
+corresponding to the front-panel buttons on the interface (although
+only the 18i20 has a physical dim button).
+
+## Routing and Mixing
+
+The routing window allows (almost) complete control of signal routing
+between the hardware inputs/outputs, internal mixer, and PCM (USB)
+inputs/outputs.
+
+The routing and mixing capabilities of the big 4th Gen interfaces are
+the same in concept as the older interfaces, but the mixer inputs are
+fixed and not shown in the routing window as there are too many to
+sensibly display.
+
+From the main window, open the Routing window with the View → Routing
+menu option or pressing Ctrl-R:
+
+![4th Gen 16i16 Routing](../img/scarlett-4th-gen-16i16-routing.png)
+
+To manage the routing connections:
+
+- Click and drag from a source to a sink or a sink to a source to
+  connect them. Audio from the source will then be sent to that sink.
+
+- Click on a source or a sink to clear the links connected to that
+  source/sink.
+
+Note that a sink can only be connected to one source, but one source
+can be connected to many sinks. If you want a sink to receive input
+from more than one source, connect the sinks to mixer outputs:
+
+- Connect mixer outputs to the sinks that you want to receive the
+  mixed audio
+- Use the Mixer window to set the amount of each mixer input that is
+  sent to each mixer output
+
+The Presets menu can be used to clear all connections, or to set up
+common configurations:
+
+- The “Direct” preset sets up the usual configuration using the
+  interface as a regular audio interface by connecting:
+
+  - all Hardware Inputs to PCM Inputs
+  - all PCM Outputs to Hardware Outputs
+
+- The “Preamp” preset connects all Hardware Inputs to Hardware
+  Outputs.
+
+- The “Stereo Out” preset connects PCM 1 and 2 Outputs to pairs of
+  Hardware Outputs.
+
+To adjust the routing:
+
+- Click and drag from a source to a sink or a sink to a source to
+  connect them. Audio from the source will then be sent to that sink.
+
+- Click on a source or a sink to clear the links connected to that
+  source/sink.
+
+Note that a sink can only be connected to one source, but one source
+can be connected to many sinks.
+
+To adjust the mixer output levels:
+
+1) Open the mixer window with the main window View → Mixer menu
+   option, or press Ctrl-M.
+
+2) Mixer levels can be adjusted with your keyboard or mouse in the
+   same way as the [Gain Controls](#gain).
+
+## Levels
+
+The meters show the levels seen by the interface at every routing
+source as well as the analogue outputs. Open this window by selecting
+the View → Levels menu option or pressing Ctrl-L.
+
+![Levels](../img/window-levels-4th-gen-big.png)
+
+Look at this in conjunction with the routing window to understand
+which meter corresponds to which source or sink.
+
+Thanks for reading this far! If you appreciate the hundreds of hours
+of work that went into the kernel driver, the control panel, and this
+documentation, please consider supporting the author with a
+[donation](../README.md#donations).
--- a/docs/iface-4th-gen-small.md
+++ b/docs/iface-4th-gen-small.md
@@ -1,9 +1,9 @@
-# ALSA Scarlett2 Control Panel
+# ALSA Scarlett Control Panel

-## Scarlett 4th Gen Interfaces
+## Scarlett Small 4th Gen Interfaces

-This document describes how to use the ALSA Scarlett2 Control Panel
-with the Scarlett 4th Gen interfaces:
+This document describes how to use the ALSA Scarlett Control Panel
+with the small Scarlett 4th Gen interfaces:

 - Scarlett 4th Gen Solo, 2i2, and 4i4

@@ -39,7 +39,7 @@ The main window for the Solo and 2i2 interfaces is shown below; the
 Monitor control, and can show the position of the front panel volume
 knobs.

-![Main Window](../img/iface-4th-gen.png)
+![Main Window](../img/iface-4th-gen-small.png)

 ### Global Controls

@@ -204,10 +204,7 @@ Important Notes:
 - The Focusrite Control 2 software can’t control most of this routing,
  so if you make changes here and then want to use Focusrite Control
  2, you’ll probably need to reset the routing back to the factory
-  default settings. There’s currently no way to reset to factory
-  default settings from the Focusrite Control 2 software; you’ll need
-  to use the [Reset Configuration](USAGE.md#startup-controls) option
-  in this software, or the `scarlett2` utility.
+  default settings.

 To adjust the routing:

@@ -338,7 +335,7 @@ sink: Hardware Outputs, Mixer Inputs, DSP Inputs, and PCM Inputs. Open
 this window by selecting the View → Levels menu option or pressing
 Ctrl-L.

-![Levels](../img/window-levels-4th-gen.gif)
+![Levels](../img/window-levels-4th-gen-small.gif)

 Look at this in conjunction with the routing window to understand
 which meter corresponds to which source or sink.
--- a/docs/iface-large.md
+++ b/docs/iface-large.md
@@ -1,8 +1,8 @@
-# ALSA Scarlett2 Control Panel
+# ALSA Scarlett Control Panel

 ## Large Scarlett 2nd and 3rd Gen and Clarett Interfaces

-This document describes how to use the ALSA Scarlett2 Control Panel
+This document describes how to use the ALSA Scarlett Control Panel
 with the larger Scarlett 2nd Gen, 3rd Gen, and Clarett USB interfaces:

 - Scarlett 2nd Gen 6i6, 18i8, 18i20
--- a/docs/iface-small.md
+++ b/docs/iface-small.md
@@ -1,4 +1,4 @@
-# ALSA Scarlett2 Control Panel
+# ALSA Scarlett Control Panel

 ## Small Scarlett 3rd Gen Interfaces

--- a/img/alsa-scarlett-gui.png
+++ b/img/alsa-scarlett-gui.png
--- a/img/iface-4th-gen-big.png
+++ b/img/iface-4th-gen-big.png
--- a/img/iface-4th-gen-small.png
+++ b/img/iface-4th-gen-small.png
--- a/img/iface-none.png
+++ b/img/iface-none.png
--- a/img/scarlett-1st-gen-6i6-routing.png
+++ b/img/scarlett-1st-gen-6i6-routing.png
--- a/img/scarlett-4th-gen-16i16-routing.png
+++ b/img/scarlett-4th-gen-16i16-routing.png
--- a/img/window-levels-4th-gen-big.png
+++ b/img/window-levels-4th-gen-big.png
--- a/img/window-levels-4th-gen-small.gif
+++ b/img/window-levels-4th-gen-small.gif
--- a/img/window-levels-4th-gen.gif
+++ b/img/window-levels-4th-gen.gif
--- a/src/Makefile
+++ b/src/Makefile
@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+# SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 # SPDX-License-Identifier: GPL-3.0-or-later

 # Credit to Tom Tromey and Paul D. Smith:
@@ -12,8 +12,9 @@ VERSION := $(shell \
 DEPDIR := .deps
 DEPFLAGS = -MT $@ -MMD -MP -MF $(DEPDIR)/$*.d

-CFLAGS ?= -ggdb -fno-omit-frame-pointer -O2
-CFLAGS += -Wall -Werror -D_FORTIFY_SOURCE=2
+CFLAGS ?= -ggdb -fno-omit-frame-pointer -fPIE -O2
+CFLAGS += -Wall -Werror
+CFLAGS += -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3
 CFLAGS += -DVERSION=\"$(VERSION)\"
 CFLAGS += -Wno-error=deprecated-declarations

@@ -26,7 +27,7 @@ CFLAGS += $(shell $(PKG_CONFIG) --cflags alsa)
 LDFLAGS += $(shell $(PKG_CONFIG) --libs glib-2.0)
 LDFLAGS += $(shell $(PKG_CONFIG) --libs gtk4)
 LDFLAGS += $(shell $(PKG_CONFIG) --libs alsa)
-LDFLAGS += -lm -lcrypto
+LDFLAGS += -lm -lcrypto -pie

 COMPILE.c = $(CC) $(DEPFLAGS) $(CFLAGS) -c

@@ -52,7 +53,7 @@ GLIB_COMPILE_RESOURCES := $(shell $(PKG_CONFIG) --variable=glib_compile_resource

 all: $(TARGET) $(DESKTOP_FILE)

-clean:
+clean: depclean
 	rm -f $(TARGET) $(DESKTOP_FILE) $(OBJS) $(XML_OBJ)

 depclean:
@@ -66,7 +67,7 @@ $(DEPFILES):
 include $(wildcard $(DEPFILES))

 $(TARGET): $(OBJS)
-	cc -o $(TARGET) $(OBJS) ${LDFLAGS}
+	$(CC) -o $(TARGET) $(OBJS) ${LDFLAGS}

 ifeq ($(PREFIX),)
  PREFIX := /usr/local
--- a/src/about.c
+++ b/src/about.c
@@ -1,8 +1,10 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "about.h"

+static GdkTexture *logo = NULL;
+
 void activate_about(
  GSimpleAction *action,
  GVariant      *parameter,
@@ -15,18 +17,23 @@ void activate_about(
    NULL
  };

+  if (!logo)
+    logo = gdk_texture_new_from_resource(
+      "/vu/b4/alsa-scarlett-gui/icons/vu.b4.alsa-scarlett-gui.png"
+    );
+
  gtk_show_about_dialog(
    w,
-    "program-name", "ALSA Scarlett2 Control Panel",
+    "program-name", "ALSA Scarlett Control Panel",
    "version", "Version " VERSION,
    "comments",
      "Gtk4 GUI for the ALSA controls presented by the\n"
-      "Linux kernel Focusrite Scarlett2 Mixer Driver",
+      "Linux kernel Focusrite USB drivers",
    "website", "https://github.com/geoffreybennett/alsa-scarlett-gui",
-    "copyright", "Copyright 2022-2024 Geoffrey D. Bennett",
+    "copyright", "Copyright 2022-2025 Geoffrey D. Bennett",
    "license-type", GTK_LICENSE_GPL_3_0,
-    "logo-icon-name", "alsa-scarlett-gui-logo",
-    "title", "About ALSA Scarlett2 Mixer Interface",
+    "logo", logo,
+    "title", "About ALSA Scarlett Mixer Interface",
    "authors", authors,
    NULL
  );
--- a/src/about.h
+++ b/src/about.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/alsa-scarlett-gui-resources.xml
+++ b/src/alsa-scarlett-gui-resources.xml
@@ -1,8 +1,12 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <gresources>
  <gresource prefix="/vu/b4/alsa-scarlett-gui/icons">
-    <file alias="alsa-scarlett-gui-logo.png">img/alsa-scarlett-gui-logo.png</file>
+    <file alias="vu.b4.alsa-scarlett-gui.png">img/vu.b4.alsa-scarlett-gui.png</file>
    <file alias="socket.svg">img/socket.svg</file>
+    <file alias="audio-volume-high.svg">img/audio-volume-high.svg</file>
+    <file alias="audio-volume-low.svg">img/audio-volume-low.svg</file>
+    <file alias="audio-volume-medium.svg">img/audio-volume-medium.svg</file>
+    <file alias="audio-volume-muted.svg">img/audio-volume-muted.svg</file>
  </gresource>
  <gresource prefix="/vu/b4/alsa-scarlett-gui">
    <file>alsa-scarlett-gui.css</file>
--- a/src/alsa-scarlett-gui.css
+++ b/src/alsa-scarlett-gui.css
@@ -55,7 +55,7 @@
  border-radius: 3px;
 }

-.route-label:hover {
+.route-label-hover {
  background: #801010;
  outline: 2px solid #801010;
 }
@@ -65,6 +65,14 @@
  background: #801010;
 }

+.mixer-label {
+}
+
+.mixer-label-hover {
+  font-weight: bold;
+  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
+}
+
 label.gain {
  font-size: smaller;
 }
@@ -83,7 +91,7 @@ label.gain {
 }

 .window-frame button:focus:focus-visible {
-  outline-color: #801010;
+  outline: 2px solid #801010;
 }

 /* padding doesn't work when selected with .window-frame, so use
@@ -118,6 +126,11 @@ button.toggle {
  filter: none;
 }

+.window-frame button.fixed label {
+  color: #ffffff;
+  filter: none;
+}
+
 /* Combobox controls that are always disabled because they indicate status */
 .window-frame combobox.fixed > box > button {
  color: #ffffff;
@@ -146,6 +159,27 @@ button.toggle {
  text-shadow: 0 0 5px #0000ff, 0 0 15px #0000ff;
 }

+.window-frame button.speaker-switching-enable:checked {
+  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
+}
+
+.window-frame button.speaker-switching-alt {
+  color: #ffffff;
+  text-shadow: 0 0 5px #00ff00, 0 0 15px #00c000;
+}
+
+.window-frame button.speaker-switching-alt:checked {
+  text-shadow: 0 0 5px #ff0000, 0 0 15px #c00000;
+}
+
+.window-frame button.talkback-enable:checked {
+  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
+}
+
+.window-frame button.talk:checked {
+  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
+}
+
 /* orange */
 .window-frame .vocaster button.autogain:checked {
  text-shadow: 0 0 5px #ffc000, 0 0 15px #ffc000;
@@ -205,6 +239,10 @@ button.toggle {
  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
 }

+.window-frame button.gain-switch:checked {
+  text-shadow: 0 0 5px #00c000, 0 0 15px #00c000;
+}
+
 .window-frame button.phantom:checked {
  text-shadow: 0 0 5px #ff0000, 0 0 15px #c00000;
 }
--- a/src/alsa-sim.c
+++ b/src/alsa-sim.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "alsa.h"
@@ -99,6 +99,53 @@ static void alsa_parse_enum_items(
  }
 }

+static void alsa_parse_int_array(
+  snd_config_t *node,
+  long        **int_values
+) {
+  int count = snd_config_is_array(node);
+  if (count < 0) {
+    printf("error: parse int array value %d\n", count);
+    return;
+  }
+
+  *int_values = calloc(count, sizeof(long));
+
+  int item_num = 0;
+
+  snd_config_iterator_t i, next;
+  snd_config_for_each(i, next, node) {
+    snd_config_t *node = snd_config_iterator_entry(i);
+
+    const char *key;
+
+    int err = snd_config_get_id(node, &key);
+    if (err < 0)
+      fatal_alsa_error("snd_config_get_id error", err);
+
+    int type = snd_config_get_type(node);
+
+    if (type == SND_CONFIG_TYPE_STRING) {
+      const char *string_value;
+
+      err = snd_config_get_string(node, &string_value);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_string error", err);
+
+      if (strcmp(string_value, "true") == 0)
+        (*int_values)[item_num++] = 1;
+
+    } else if (type == SND_CONFIG_TYPE_INTEGER) {
+      long int_value;
+      err = snd_config_get_integer(node, &int_value);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_integer error", err);
+
+      (*int_values)[item_num++] = int_value;
+    }
+  }
+}
+
 // parse a comment node and update elem, e.g.:
 //
 // comment {
@@ -133,7 +180,7 @@ static void alsa_parse_comment_node(
      if (err < 0)
        fatal_alsa_error("snd_config_get_string error", err);
      if (strstr(access, "write"))
-        elem->writable = 1;
+        elem->is_writable = 1;
    } else if (strcmp(key, "type") == 0) {
      if (type != SND_CONFIG_TYPE_STRING) {
        printf("type type not string\n");
@@ -149,6 +196,14 @@ static void alsa_parse_comment_node(
        elem->type = SND_CTL_ELEM_TYPE_ENUMERATED;
      else if (strcmp(type, "INTEGER") == 0)
        elem->type = SND_CTL_ELEM_TYPE_INTEGER;
+    } else if (strcmp(key, "count") == 0) {
+      long count;
+
+      err = snd_config_get_integer(node, &count);
+      if (err < 0)
+        fatal_alsa_error("snd_config_get_integer error", err);
+
+      elem->count = count;
    } else if (strcmp(key, "item") == 0) {
      alsa_parse_enum_items(node, elem);
    } else if (strcmp(key, "range") == 0) {
@@ -176,7 +231,7 @@ static void alsa_parse_comment_node(
      err = snd_config_get_integer(node, &dbmin);
      if (err < 0)
        fatal_alsa_error("snd_config_get_integer error", err);
-      elem->min_dB = dbmin / 100;
+      elem->min_cdB = dbmin;
    } else if (strcmp(key, "dbmax") == 0) {
      if (type != SND_CONFIG_TYPE_INTEGER) {
        printf("dbmax type not integer\n");
@@ -186,14 +241,14 @@ static void alsa_parse_comment_node(
      err = snd_config_get_integer(node, &dbmax);
      if (err < 0)
        fatal_alsa_error("snd_config_get_integer error", err);
-      elem->max_dB = dbmax / 100;
+      elem->max_cdB = dbmax;
    }
  }
 }

 static int alsa_config_to_new_elem(
-  snd_config_t     *config,
-  struct alsa_elem *elem
+  struct alsa_card *card,
+  snd_config_t     *config
 ) {
  const char *s;
  int id;
@@ -202,8 +257,11 @@ static int alsa_config_to_new_elem(
  int value_type = -1;
  char *string_value = NULL;
  long int_value;
+  long *int_values = NULL;
  int err;

+  struct alsa_elem elem = {};
+
  err = snd_config_get_id(config, &s);
  if (err < 0)
    fatal_alsa_error("snd_config_get_id error", err);
@@ -260,11 +318,14 @@ static int alsa_config_to_new_elem(
          fatal_alsa_error("snd_config_get_string error", err);
        string_value = strdup(s);
      } else if (type == SND_CONFIG_TYPE_COMPOUND) {
-        elem->count = snd_config_is_array(node);
+        elem.count = snd_config_is_array(node);
+
        if (strcmp(name, "Level Meter") == 0) {
          seen_value = 1;
          value_type = SND_CONFIG_TYPE_INTEGER;
          int_value = 0;
+        } else if (elem.count == 2 && strncmp(name, "Master", 6) == 0) {
+          alsa_parse_int_array(node, &int_values);
        } else {
          goto fail;
        }
@@ -278,7 +339,11 @@ static int alsa_config_to_new_elem(

    // comment node?
    } else if (strcmp(key, "comment") == 0) {
-      alsa_parse_comment_node(node, elem);
+      alsa_parse_comment_node(node, &elem);
+
+    // this isn't needed
+    } else if (strcmp(key, "index") == 0) {
+
    } else {
      printf("skipping unknown node %s for %d\n", key, id);
      goto fail;
@@ -309,21 +374,21 @@ static int alsa_config_to_new_elem(

  // integer in config
  if (value_type == SND_CONFIG_TYPE_INTEGER) {
-    elem->value = int_value;
+    elem.value = int_value;

  // string in config
  } else if (value_type == SND_CONFIG_TYPE_STRING) {

    // translate boolean true/false
-    if (elem->type == SND_CTL_ELEM_TYPE_BOOLEAN) {
+    if (elem.type == SND_CTL_ELEM_TYPE_BOOLEAN) {
      if (strcmp(string_value, "true") == 0)
-        elem->value = 1;
+        elem.value = 1;

    // translate enum string value to integer
-    } else if (elem->type == SND_CTL_ELEM_TYPE_ENUMERATED) {
-      for (int i = 0; i < elem->item_count; i++) {
-        if (strcmp(string_value, elem->item_names[i]) == 0) {
-          elem->value = i;
+    } else if (elem.type == SND_CTL_ELEM_TYPE_ENUMERATED) {
+      for (int i = 0; i < elem.item_count; i++) {
+        if (strcmp(string_value, elem.item_names[i]) == 0) {
+          elem.value = i;
          break;
        }
      }
@@ -334,11 +399,30 @@ static int alsa_config_to_new_elem(
    }
  }

-  elem->numid = id;
-  elem->name = name;
+  elem.card = card;
+  elem.numid = id;
+  elem.name = name;
+
+  // duplicate the element for each channel except for the Level Meter
+  int count = elem.count;
+
+  if (strcmp(elem.name, "Level Meter") == 0)
+    count = 1;
+
+  // for each channel, create a new element and add it to the card
+  // incrementing the index each time
+  for (int i = 0; i < count; i++, elem.index++) {
+    if (count > 1)
+      elem.value = int_values[i];
+
+    int array_len = card->elems->len;
+    g_array_set_size(card->elems, array_len + 1);
+    g_array_index(card->elems, struct alsa_elem, array_len) = elem;
+  }

  free(iface);
  free(string_value);
+  free(int_values);

  return 0;

@@ -346,6 +430,7 @@ fail:
  free(iface);
  free(name);
  free(string_value);
+  free(int_values);

  return -1;
 }
@@ -370,18 +455,8 @@ static void alsa_config_to_new_card(
    if (snd_config_get_type(config) != SND_CONFIG_TYPE_COMPOUND)
      continue;

-    struct alsa_elem elem = {};
-    elem.card = card;
-
    // create the element
-    int err = alsa_config_to_new_elem(node, &elem);
-
-    if (err)
-      continue;
-
-    if (card->elems->len <= elem.numid)
-      g_array_set_size(card->elems, elem.numid + 1);
-    g_array_index(card->elems, struct alsa_elem, elem.numid) = elem;
+    alsa_config_to_new_elem(card, node);
  }
 }

@@ -433,5 +508,8 @@ void create_sim_from_file(GtkWindow *w, char *fn) {

  snd_config_delete(config);

+  alsa_set_lr_nums(card);
+  alsa_get_routing_controls(card);
+
  create_card_window(card);
 }
--- a/src/alsa-sim.h
+++ b/src/alsa-sim.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/alsa.c
+++ b/src/alsa.c
@@ -1,23 +1,37 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <sys/inotify.h>
+#include <alsa/sound/uapi/tlv.h>

 #include "alsa.h"
 #include "scarlett2-firmware.h"
 #include "stringhelper.h"
 #include "window-iface.h"

-#define MAX_TLV_RANGE_SIZE 256
+#define MAX_TLV_RANGE_SIZE 1024
+
+// TLV type for channel labels
+#ifndef SNDRV_CTL_TLVT_FCP_CHANNEL_LABELS
+#define SNDRV_CTL_TLVT_FCP_CHANNEL_LABELS 0x110
+#endif

 // names for the port categories
 const char *port_category_names[PC_COUNT] = {
+  NULL,
  "Hardware Outputs",
  "Mixer Inputs",
  "DSP Inputs",
  "PCM Inputs"
 };

+// names for the hardware types
+const char *hw_type_names[HW_TYPE_COUNT] = {
+  "Analogue",
+  "S/PDIF",
+  "ADAT"
+};
+
 // global array of cards
 static GArray *alsa_cards;

@@ -45,7 +59,7 @@ void fatal_alsa_error(const char *msg, int err) {
 //

 // return the element with the exact matching name
-struct alsa_elem *get_elem_by_name(GArray *elems, char *name) {
+struct alsa_elem *get_elem_by_name(GArray *elems, const char *name) {
  for (int i = 0; i < elems->len; i++) {
    struct alsa_elem *elem = &g_array_index(elems, struct alsa_elem, i);

@@ -60,7 +74,7 @@ struct alsa_elem *get_elem_by_name(GArray *elems, char *name) {
 }

 // return the first element with a name starting with the given prefix
-struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix) {
+struct alsa_elem *get_elem_by_prefix(GArray *elems, const char *prefix) {
  int prefix_len = strlen(prefix);

  for (int i = 0; i < elems->len; i++) {
@@ -76,12 +90,31 @@ struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix) {
  return NULL;
 }

+// return the first element with a name containing the given substring
+struct alsa_elem *get_elem_by_substr(GArray *elems, const char *substr) {
+  for (int i = 0; i < elems->len; i++) {
+    struct alsa_elem *elem = &g_array_index(elems, struct alsa_elem, i);
+
+    if (!elem->card)
+      continue;
+
+    if (strstr(elem->name, substr))
+      return elem;
+  }
+
+  return NULL;
+}
+
 // find the maximum number in the matching elements
 // search by element name prefix and substring
 // e.g. get_max_elem_by_name(elems, "Line", "Pad Capture Switch")
 // will return 8 when the last pad capture switch is
 // "Line In 8 Pad Capture Switch"
-int get_max_elem_by_name(GArray *elems, char *prefix, char *needle) {
+int get_max_elem_by_name(
+  GArray *elems,
+  const char *prefix,
+  const char *needle
+) {
  int max = 0;
  int l = strlen(prefix);

@@ -106,25 +139,6 @@ int get_max_elem_by_name(GArray *elems, char *prefix, char *needle) {
  return max;
 }

-// return true if the element is an routing sink enum, e.g.:
-// PCM xx Capture Enum
-// Mixer Input xx Capture Enum
-// Analogue Output xx Playback Enum
-// S/PDIF Output xx Playback Enum
-// ADAT Output xx Playback Enum
-int is_elem_routing_snk(struct alsa_elem *elem) {
-  if (strstr(elem->name, "Capture Enum") && (
-       strncmp(elem->name, "PCM ", 4) == 0 ||
-       strncmp(elem->name, "Mixer Input ", 12) == 0 ||
-       strncmp(elem->name, "DSP Input ", 10) == 0
-     ))
-    return 1;
-  if (strstr(elem->name, "Output") &&
-      strstr(elem->name, "Playback Enum"))
-    return 1;
-  return 0;
-}
-
 // add a callback to the list of callbacks for this element
 void alsa_elem_add_callback(
  struct alsa_elem *elem,
@@ -182,11 +196,11 @@ long alsa_get_elem_value(struct alsa_elem *elem) {

  int type = elem->type;
  if (type == SND_CTL_ELEM_TYPE_BOOLEAN) {
-    return snd_ctl_elem_value_get_boolean(elem_value, 0);
+    return snd_ctl_elem_value_get_boolean(elem_value, elem->index);
  } else if (type == SND_CTL_ELEM_TYPE_ENUMERATED) {
-    return snd_ctl_elem_value_get_enumerated(elem_value, 0);
+    return snd_ctl_elem_value_get_enumerated(elem_value, elem->index);
  } else if (type == SND_CTL_ELEM_TYPE_INTEGER) {
-    return snd_ctl_elem_value_get_integer(elem_value, 0);
+    return snd_ctl_elem_value_get_integer(elem_value, elem->index);
  } else {
    fprintf(
      stderr,
@@ -237,14 +251,15 @@ void alsa_set_elem_value(struct alsa_elem *elem, long value) {

  snd_ctl_elem_value_alloca(&elem_value);
  snd_ctl_elem_value_set_numid(elem_value, elem->numid);
+  snd_ctl_elem_read(elem->card->handle, elem_value);

  int type = elem->type;
  if (type == SND_CTL_ELEM_TYPE_BOOLEAN) {
-    snd_ctl_elem_value_set_boolean(elem_value, 0, value);
+    snd_ctl_elem_value_set_boolean(elem_value, elem->index, value);
  } else if (type == SND_CTL_ELEM_TYPE_ENUMERATED) {
-    snd_ctl_elem_value_set_enumerated(elem_value, 0, value);
+    snd_ctl_elem_value_set_enumerated(elem_value, elem->index, value);
  } else if (type == SND_CTL_ELEM_TYPE_INTEGER) {
-    snd_ctl_elem_value_set_integer(elem_value, 0, value);
+    snd_ctl_elem_value_set_integer(elem_value, elem->index, value);
  } else {
    fprintf(
      stderr,
@@ -262,7 +277,7 @@ void alsa_set_elem_value(struct alsa_elem *elem, long value) {
 // return whether the element can be modified (is writable)
 int alsa_get_elem_writable(struct alsa_elem *elem) {
  if (elem->card->num == SIMULATED_CARD_NUM)
-    return elem->writable;
+    return elem->is_writable;

  snd_ctl_elem_info_t *elem_info;

@@ -270,7 +285,23 @@ int alsa_get_elem_writable(struct alsa_elem *elem) {
  snd_ctl_elem_info_set_numid(elem_info, elem->numid);
  snd_ctl_elem_info(elem->card->handle, elem_info);

-  return snd_ctl_elem_info_is_writable(elem_info);
+  return snd_ctl_elem_info_is_writable(elem_info) &&
+         !snd_ctl_elem_info_is_locked(elem_info);
+}
+
+// return whether the element is volatile (can change without
+// notification)
+int alsa_get_elem_volatile(struct alsa_elem *elem) {
+  if (elem->card->num == SIMULATED_CARD_NUM)
+    return elem->is_volatile;
+
+  snd_ctl_elem_info_t *elem_info;
+
+  snd_ctl_elem_info_alloca(&elem_info);
+  snd_ctl_elem_info_set_numid(elem_info, elem->numid);
+  snd_ctl_elem_info(elem->card->handle, elem_info);
+
+  return snd_ctl_elem_info_is_volatile(elem_info);
 }

 // get the number of values this element has
@@ -319,6 +350,163 @@ char *alsa_get_item_name(struct alsa_elem *elem, int i) {
 // create/destroy alsa cards
 //

+static void alsa_get_elem_tlv(struct alsa_elem *elem) {
+  struct alsa_card *card = elem->card;
+
+  if (elem->type != SND_CTL_ELEM_TYPE_INTEGER)
+    return;
+
+  snd_ctl_elem_info_t *elem_info;
+
+  snd_ctl_elem_info_alloca(&elem_info);
+  snd_ctl_elem_info_set_numid(elem_info, elem->numid);
+  snd_ctl_elem_info(card->handle, elem_info);
+
+  if (!snd_ctl_elem_info_is_tlv_readable(elem_info))
+    return;
+
+  snd_ctl_elem_id_t *elem_id;
+  unsigned int tlv[MAX_TLV_RANGE_SIZE];
+  unsigned int *dbrec;
+  int ret;
+  long min_cdB, max_cdB;
+
+  snd_ctl_elem_id_alloca(&elem_id);
+  snd_ctl_elem_id_set_numid(elem_id, elem->numid);
+
+  ret = snd_ctl_elem_tlv_read(
+    card->handle, elem_id, tlv, sizeof(tlv)
+  );
+  if (ret < 0) {
+    fprintf(stderr, "TLV read error: %s\n", snd_strerror(ret));
+    return;
+  }
+
+  // meter map
+  if (tlv[SNDRV_CTL_TLVO_TYPE] == SNDRV_CTL_TLVT_FCP_CHANNEL_LABELS) {
+    int label_data_size = tlv[SNDRV_CTL_TLVO_LEN];
+    char *label_data = (char *)&tlv[SNDRV_CTL_TLVO_LEN + 1];
+
+    // check that there are at least elem->count labels in the data
+    int label_count = 0;
+    for (int i = 0; i < label_data_size; i++) {
+      if (!label_data[i])
+        label_count++;
+    }
+
+    if (label_count < elem->count) {
+      fprintf(
+        stderr,
+        "TLV label count %d < %d\n",
+        label_count,
+        elem->count
+      );
+      return;
+    }
+
+    if (elem->count < 0 || elem->count > 255) {
+      fprintf(stderr, "TLV label count %d out of range\n", elem->count);
+      exit(1);
+    }
+
+    elem->meter_labels = calloc(elem->count, sizeof(char *));
+
+    char *cur_label = label_data;
+    for (int i = 0; i < elem->count; i++) {
+      elem->meter_labels[i] = strdup(cur_label);
+      if (!elem->meter_labels[i]) {
+        fprintf(stderr, "strdup failed\n");
+        exit(1);
+      }
+
+      cur_label += strlen(cur_label) + 1;
+    }
+
+  /* firmware version TLV contains socket location */
+  } else if (tlv[SNDRV_CTL_TLVO_TYPE] == 0x53434B54) {
+    card->fcp_socket = strdup((char *)&tlv[SNDRV_CTL_TLVO_LEN + 1]);
+
+  /* dB range */
+  } else {
+    ret = snd_tlv_parse_dB_info(tlv, sizeof(tlv), &dbrec);
+    if (ret <= 0) {
+      fprintf(stderr, "TLV parse error: %s\n", snd_strerror(ret));
+      return;
+    }
+
+    int min_val = snd_ctl_elem_info_get_min(elem_info);
+    int max_val = snd_ctl_elem_info_get_max(elem_info);
+
+    ret = snd_tlv_get_dB_range(
+      dbrec, min_val, max_val, &min_cdB, &max_cdB
+    );
+    if (ret != 0) {
+      fprintf(stderr, "TLV range error: %s\n", snd_strerror(ret));
+      return;
+    }
+
+    elem->min_val = min_val;
+    elem->max_val = max_val;
+    elem->dB_type = dbrec[SNDRV_CTL_TLVO_TYPE];
+    elem->min_cdB = min_cdB;
+    elem->max_cdB = max_cdB;
+  }
+}
+
+static void alsa_get_elem(struct alsa_card *card, int numid) {
+  // allocate a temporary struct alsa_elem (will be copied later if
+  // we want to keep it)
+  struct alsa_elem alsa_elem = {};
+
+  // keep a reference to the card in the element
+  alsa_elem.card = card;
+
+  // get the control's numeric identifier (different to the index
+  // into this array)
+  alsa_elem.numid = numid;
+
+  // get the control's info
+  alsa_elem.type = alsa_get_elem_type(&alsa_elem);
+  alsa_elem.name = alsa_get_elem_name(&alsa_elem);
+  alsa_elem.count = alsa_get_elem_count(&alsa_elem);
+
+  switch (alsa_elem.type) {
+    case SND_CTL_ELEM_TYPE_BOOLEAN:
+    case SND_CTL_ELEM_TYPE_ENUMERATED:
+    case SND_CTL_ELEM_TYPE_INTEGER:
+      break;
+    default:
+      return;
+  }
+
+  if (strstr(alsa_elem.name, "Validity"))
+    return;
+  if (strstr(alsa_elem.name, "Channel Map"))
+    return;
+
+  alsa_get_elem_tlv(&alsa_elem);
+
+  // Scarlett 1st Gen driver puts two volume controls/mutes in the
+  // same element, so split them out to match the other series
+  int count = alsa_elem.count;
+
+  if (strcmp(alsa_elem.name, "Level Meter") == 0)
+    count = 1;
+
+  if (count > 2) {
+    fprintf(stderr, "element %s has count %d\n", alsa_elem.name, count);
+    count = 1;
+  }
+
+  for (int i = 0; i < count; i++, alsa_elem.lr_num++) {
+    alsa_elem.index = i;
+
+    int array_len = card->elems->len;
+    g_array_set_size(card->elems, array_len + 1);
+    g_array_index(card->elems, struct alsa_elem, array_len) = alsa_elem;
+  }
+}
+
 // scan the ALSA ctl element list container and put the useful
 // elements into the cards->elems array of struct alsa_elem
 static void alsa_get_elem_list(struct alsa_card *card) {
@@ -334,88 +522,8 @@ static void alsa_get_elem_list(struct alsa_card *card) {

  // for each element in the list
  for (int i = 0; i < count; i++) {
-
-    // allocate a temporary struct alsa_elem (will be copied later if
-    // we want to keep it)
-    struct alsa_elem alsa_elem = {};
-
-    // keep a reference to the card in the element
-    alsa_elem.card = card;
-
-    // get the control's numeric identifier (different to the index
-    // into this array)
-    alsa_elem.numid = snd_ctl_elem_list_get_numid(list, i);
-
-    // get the control's info
-    alsa_elem.type = alsa_get_elem_type(&alsa_elem);
-    alsa_elem.name = alsa_get_elem_name(&alsa_elem);
-    alsa_elem.count = alsa_get_elem_count(&alsa_elem);
-
-    switch (alsa_elem.type) {
-      case SND_CTL_ELEM_TYPE_BOOLEAN:
-      case SND_CTL_ELEM_TYPE_ENUMERATED:
-      case SND_CTL_ELEM_TYPE_INTEGER:
-        break;
-      default:
-        continue;
-    }
-
-    if (strstr(alsa_elem.name, "Validity"))
-      continue;
-    if (strstr(alsa_elem.name, "Channel Map"))
-      continue;
-
-    // get TLV info if it's a volume control
-    if (alsa_elem.type == SND_CTL_ELEM_TYPE_INTEGER) {
-      snd_ctl_elem_info_t *elem_info;
-
-      snd_ctl_elem_info_alloca(&elem_info);
-      snd_ctl_elem_info_set_numid(elem_info, alsa_elem.numid);
-      snd_ctl_elem_info(card->handle, elem_info);
-
-      if (snd_ctl_elem_info_is_tlv_readable(elem_info)) {
-        snd_ctl_elem_id_t *elem_id;
-        unsigned int tlv[MAX_TLV_RANGE_SIZE];
-        unsigned int *dbrec;
-        int ret;
-        long min_dB, max_dB;
-
-        snd_ctl_elem_id_alloca(&elem_id);
-        snd_ctl_elem_id_set_numid(elem_id, alsa_elem.numid);
-
-        ret = snd_ctl_elem_tlv_read(
-          card->handle, elem_id, tlv, sizeof(tlv)
-        );
-        if (ret < 0) {
-          fprintf(stderr, "TLV read error %d\n", ret);
-          continue;
-        }
-
-        ret = snd_tlv_parse_dB_info(tlv, sizeof(tlv), &dbrec);
-        if (ret <= 0) {
-          fprintf(stderr, "TLV parse error %d\n", ret);
-          continue;
-        }
-
-        int min_val = snd_ctl_elem_info_get_min(elem_info);
-        int max_val = snd_ctl_elem_info_get_max(elem_info);
-
-        ret = snd_tlv_get_dB_range(tlv, min_val, max_val, &min_dB, &max_dB);
-        if (ret != 0) {
-          fprintf(stderr, "TLV range error %d\n", ret);
-          continue;
-        }
-
-        alsa_elem.min_val = min_val;
-        alsa_elem.max_val = max_val;
-        alsa_elem.min_dB = min_dB / 100;
-        alsa_elem.max_dB = max_dB / 100;
-      }
-    }
-
-    if (card->elems->len <= alsa_elem.numid)
-      g_array_set_size(card->elems, alsa_elem.numid + 1);
-    g_array_index(card->elems, struct alsa_elem, alsa_elem.numid) = alsa_elem;
+    int numid = snd_ctl_elem_list_get_numid(list, i);
+    alsa_get_elem(card, numid);
  }

  // free the ALSA list
@@ -423,6 +531,227 @@ static void alsa_get_elem_list(struct alsa_card *card) {
  snd_ctl_elem_list_free(list);
 }

+static void alsa_set_elem_lr_num(struct alsa_elem *elem) {
+  const char *name = elem->name;
+  char side;
+
+  if (strncmp(name, "Master Playback", 15) == 0 ||
+      strncmp(name, "Master HW Playback", 18) == 0)
+    elem->lr_num = 0;
+
+  else if (strncmp(name, "Master", 6) == 0)
+    if (sscanf(name, "Master %d%c", &elem->lr_num, &side) != 2)
+      printf("can't parse Master '%s'\n", name);
+    else
+      elem->lr_num = elem->lr_num * 2
+                     - (side == 'L' || side == ' ')
+                     + elem->index;
+
+  else
+    elem->lr_num = get_num_from_string(name);
+}
+
+void alsa_set_lr_nums(struct alsa_card *card) {
+  for (int i = 0; i < card->elems->len; i++) {
+    struct alsa_elem *elem = &g_array_index(card->elems, struct alsa_elem, i);
+
+    alsa_set_elem_lr_num(elem);
+  }
+}
+
+static void get_routing_srcs(struct alsa_card *card) {
+  struct alsa_elem *elem = card->sample_capture_elem;
+
+  int count = alsa_get_item_count(elem);
+  card->routing_srcs = g_array_new(
+    FALSE, TRUE, sizeof(struct routing_src)
+  );
+  g_array_set_size(card->routing_srcs, count);
+
+  for (int i = 0; i < count; i++) {
+    char *name = alsa_get_item_name(elem, i);
+
+    struct routing_src *r = &g_array_index(
+      card->routing_srcs, struct routing_src, i
+    );
+    r->card = card;
+    r->id = i;
+
+    if (strcmp(name, "Off") == 0)
+      r->port_category = PC_OFF;
+    else if (strncmp(name, "Mix", 3) == 0)
+      r->port_category = PC_MIX;
+    else if (strncmp(name, "DSP", 3) == 0)
+      r->port_category = PC_DSP;
+    else if (strncmp(name, "PCM", 3) == 0)
+      r->port_category = PC_PCM;
+    else {
+      r->port_category = PC_HW;
+
+      if (strncmp(name, "Analog", 6) == 0)
+        r->hw_type = HW_TYPE_ANALOGUE;
+      else if (strncmp(name, "S/PDIF", 6) == 0)
+        r->hw_type = HW_TYPE_SPDIF;
+      else if (strncmp(name, "SPDIF", 5) == 0)
+        r->hw_type = HW_TYPE_SPDIF;
+      else if (strncmp(name, "ADAT", 4) == 0)
+        r->hw_type = HW_TYPE_ADAT;
+    }
+
+    r->name = name;
+    r->lr_num =
+      r->port_category == PC_MIX
+        ? name[4] - 'A' + 1
+        : get_num_from_string(name);
+
+    r->port_num = card->routing_in_count[r->port_category]++;
+  }
+
+  assert(card->routing_in_count[PC_MIX] <= MAX_MIX_OUT);
+}
+
+// return true if the element is an routing sink enum, e.g.:
+// PCM xx Capture Enum
+// Mixer Input xx Capture Enum
+// Analogue Output xx Playback Enum
+// S/PDIF Output xx Playback Enum
+// ADAT Output xx Playback Enum
+//
+// or new style:
+// PCM xx Capture Enum
+// Mixer xx Capture Enum
+// Analogue xx Playback Enum
+// S/PDIF xx Playback Enum
+// ADAT xx Playback Enum
+
+static int is_elem_routing_snk(struct alsa_elem *elem) {
+  if (strstr(elem->name, "Capture Route") ||
+      strstr(elem->name, "Input Playback Route") ||
+      strstr(elem->name, "Source Playback Enu"))
+    return 1;
+
+  if (strstr(elem->name, "Capture Enum") && (
+       strncmp(elem->name, "PCM ", 4) == 0 ||
+       strncmp(elem->name, "Mixer ", 6) == 0 ||
+       strncmp(elem->name, "DSP ", 4) == 0
+     ))
+    return 1;
+
+  if (strstr(elem->name, "Playback Enum") && (
+       strncmp(elem->name, "Analogue ", 9) == 0 ||
+       strncmp(elem->name, "S/PDIF ", 7) == 0 ||
+       strncmp(elem->name, "ADAT ", 5) == 0
+     ))
+    return 1;
+
+  return 0;
+}
+
+static void get_routing_snks(struct alsa_card *card) {
+  GArray *elems = card->elems;
+
+  int count = 0;
+
+  // count and label routing snks
+  for (int i = 0; i < elems->len; i++) {
+    struct alsa_elem *elem = &g_array_index(elems, struct alsa_elem, i);
+
+    if (!elem->card)
+      continue;
+
+    if (!is_elem_routing_snk(elem))
+      continue;
+
+    elem->is_routing_snk = 1;
+
+    if (strncmp(elem->name, "Mixer", 5) == 0 ||
+        strncmp(elem->name, "Matrix", 6) == 0) {
+      elem->port_category = PC_MIX;
+
+      if (!alsa_get_elem_writable(elem))
+        card->has_fixed_mixer_inputs = 1;
+
+    } else if (strncmp(elem->name, "DSP", 3) == 0) {
+      elem->port_category = PC_DSP;
+    } else if (strncmp(elem->name, "PCM", 3) == 0 ||
+               strncmp(elem->name, "Input Source", 12) == 0) {
+      elem->port_category = PC_PCM;
+    } else if (strstr(elem->name, "Playback Enu")) {
+      elem->port_category = PC_HW;
+
+      if (strncmp(elem->name, "Analog", 6) == 0)
+        elem->hw_type = HW_TYPE_ANALOGUE;
+      else if (strncmp(elem->name, "S/PDIF", 6) == 0 ||
+               strstr(elem->name, "SPDIF"))
+        elem->hw_type = HW_TYPE_SPDIF;
+      else if (strstr(elem->name, "ADAT"))
+        elem->hw_type = HW_TYPE_ADAT;
+    } else {
+      printf("unknown mixer routing elem %s\n", elem->name);
+      continue;
+    }
+
+    if (elem->lr_num <= 0) {
+      fprintf(stderr, "routing sink %s had no number\n", elem->name);
+      continue;
+    }
+
+    count++;
+  }
+
+  // create an array of routing snks pointing to those elements
+  card->routing_snks = g_array_new(
+    FALSE, TRUE, sizeof(struct routing_snk)
+  );
+  g_array_set_size(card->routing_snks, count);
+
+  // count through card->routing_snks
+  int j = 0;
+
+  for (int i = 0; i < elems->len; i++) {
+    struct alsa_elem *elem = &g_array_index(elems, struct alsa_elem, i);
+
+    if (!elem->is_routing_snk)
+      continue;
+
+    struct routing_snk *r = &g_array_index(
+      card->routing_snks, struct routing_snk, j
+    );
+    r->idx = j;
+    j++;
+    r->elem = elem;
+    elem->port_num = card->routing_out_count[elem->port_category]++;
+  }
+
+  assert(j == count);
+}
+
+void alsa_get_routing_controls(struct alsa_card *card) {
+
+  // check that we can find a routing control
+  card->sample_capture_elem =
+    get_elem_by_name(card->elems, "PCM 01 Capture Enum");
+  if (!card->sample_capture_elem)
+    card->sample_capture_elem =
+      get_elem_by_name(card->elems, "PCM 1 Capture Enum");
+  if (!card->sample_capture_elem)
+    card->sample_capture_elem =
+      get_elem_by_name(card->elems, "Input Source 01 Capture Route");
+
+  if (!card->sample_capture_elem) {
+    fprintf(
+      stderr,
+      "can't find routing control PCM 01 Capture Enum or "
+      "Input Source 01 Capture Route\n"
+    );
+
+    return;
+  }
+
+  get_routing_srcs(card);
+  get_routing_snks(card);
+}
+
 static void alsa_elem_change(struct alsa_elem *elem) {
  if (!elem || !elem->callbacks)
    return;
@@ -437,6 +766,27 @@ static void alsa_elem_change(struct alsa_elem *elem) {
  }
 }

+static void card_destroy_callback(void *data) {
+  struct alsa_card *card = data;
+
+  // close the windows associated with this card
+  destroy_card_window(card);
+
+  // TODO: there is more to free
+  free(card->device);
+  free(card->serial);
+  free(card->name);
+  free(card);
+
+  // go through the alsa_cards array and clear the entry for this card
+  for (int i = 0; i < alsa_cards->len; i++) {
+    struct alsa_card **card_ptr =
+      &g_array_index(alsa_cards, struct alsa_card *, i);
+    if (*card_ptr == card)
+      *card_ptr = NULL;
+  }
+}
+
 static gboolean alsa_card_callback(
  GIOChannel    *source,
  GIOCondition   condition,
@@ -444,16 +794,13 @@ static gboolean alsa_card_callback(
 ) {
  struct alsa_card *card = data;
  snd_ctl_event_t *event;
-  unsigned int mask;
-  int err, numid;
-  struct alsa_elem *elem;

  snd_ctl_event_alloca(&event);
  if (!card->handle) {
    printf("oops, no card handle??\n");
    return 0;
  }
-  err = snd_ctl_read(card->handle, event);
+  int err = snd_ctl_read(card->handle, event);
  if (err == 0) {
    printf("alsa_card_callback nothing to read??\n");
    return 0;
@@ -464,18 +811,27 @@ static gboolean alsa_card_callback(
    printf("card_callback_error %d\n", err);
    exit(1);
  }
+
  if (snd_ctl_event_get_type(event) != SND_CTL_EVENT_ELEM)
    return 1;

-  numid = snd_ctl_event_elem_get_numid(event);
-  elem = &g_array_index(card->elems, struct alsa_elem, numid);
-  if (elem->numid != numid)
+  int numid = snd_ctl_event_elem_get_numid(event);
+  unsigned int mask = snd_ctl_event_elem_get_mask(event);
+
+  if (mask == SND_CTL_EVENT_MASK_REMOVE) {
+    card_destroy_callback(card);
+    return 0;
+  }
+
+  if (!(mask & (SND_CTL_EVENT_MASK_VALUE | SND_CTL_EVENT_MASK_INFO)))
    return 1;

-  mask = snd_ctl_event_elem_get_mask(event);
+  for (int i = 0; i < card->elems->len; i++) {
+    struct alsa_elem *elem = &g_array_index(card->elems, struct alsa_elem, i);

-  if (mask & (SND_CTL_EVENT_MASK_VALUE | SND_CTL_EVENT_MASK_INFO))
-    alsa_elem_change(elem);
+    if (elem->numid == numid)
+      alsa_elem_change(elem);
+  }

  return 1;
 }
@@ -524,27 +880,6 @@ struct alsa_card *card_create(int card_num) {
  return card;
 }

-static void card_destroy_callback(void *data) {
-  struct alsa_card *card = data;
-
-  // close the windows associated with this card
-  destroy_card_window(card);
-
-  // TODO: there is more to free
-  free(card->device);
-  free(card->serial);
-  free(card->name);
-  free(card);
-
-  // go through the alsa_cards array and clear the entry for this card
-  for (int i = 0; i < alsa_cards->len; i++) {
-    struct alsa_card **card_ptr =
-      &g_array_index(alsa_cards, struct alsa_card *, i);
-    if (*card_ptr == card)
-      *card_ptr = NULL;
-  }
-}
-
 static void alsa_add_card_callback(struct alsa_card *card) {
  card->io_channel = g_io_channel_unix_new(card->pfd.fd);
  card->event_source_id = g_io_add_watch_full(
@@ -776,14 +1111,18 @@ static void alsa_scan_cards(void) {
    card->handle = ctl;

    alsa_get_elem_list(card);
+    alsa_set_lr_nums(card);
+    alsa_get_routing_controls(card);
+
    alsa_subscribe(card);
    alsa_get_usbid(card);
    alsa_get_serial_number(card);
-    card->best_firmware_version = scarlett2_get_best_firmware_version(card->pid);
+    card->best_firmware_version =
+      scarlett2_get_best_firmware_version(card->pid);

    if (card->serial) {

-      // call the callbacks for this card
+      // call the reopen callbacks for this card
      struct reopen_callback *rc = g_hash_table_lookup(
        reopen_callbacks, card->serial
      );
--- a/src/alsa.h
+++ b/src/alsa.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
@@ -22,25 +22,28 @@ typedef void (AlsaElemCallback)(struct alsa_elem *, void *);
 // port categories for routing_src and routing_snk entries
 // must match the level meter ordering from the driver
 enum {
-  // Hardware inputs/outputs
-  PC_HW    = 0,
-
-  // Mixer inputs/outputs
-  PC_MIX   = 1,
-
-  // DSP inputs/outputs
-  PC_DSP   = 2,
-
-  // PCM inputs/outputs
-  PC_PCM   = 3,
-
-  // number of port categories
-  PC_COUNT = 4
+  PC_OFF,  // Off (the source when a sink is not connected)
+  PC_HW,   // Hardware inputs/outputs
+  PC_MIX,  // Mixer inputs/outputs
+  PC_DSP,  // DSP inputs/outputs
+  PC_PCM,  // PCM inputs/outputs
+  PC_COUNT // number of port categories
 };

 // names for the port categories
 extern const char *port_category_names[PC_COUNT];

+// hardware types
+enum {
+  HW_TYPE_ANALOGUE,
+  HW_TYPE_SPDIF,
+  HW_TYPE_ADAT,
+  HW_TYPE_COUNT
+};
+
+// names for the hardware types
+extern const char *hw_type_names[HW_TYPE_COUNT];
+
 // is a drag active, and whether dragging from a routing source or a
 // routing sink
 enum {
@@ -59,7 +62,7 @@ struct routing_src {
  // the enum id of the alsa item
  int id;

-  // PC_DSP, PC_MIX, PC_PCM, or PC_HW
+  // PC_OFF, PC_DSP, PC_MIX, PC_PCM, or PC_HW
  int port_category;

  // 0-based count within port_category
@@ -68,6 +71,9 @@ struct routing_src {
  // the alsa item name
  char *name;

+  // for PC_HW, the hardware type
+  int hw_type;
+
  // the number (or translated letter; A = 1) in the item name
  int lr_num;

@@ -82,8 +88,6 @@ struct routing_src {
 // entry in alsa_card routing_snks (routing sinks) array for alsa
 // elements that are routing sinks like Analogue Output 01 Playback
 // Enum
-// port_category is set to PC_DSP, PC_MIX, PC_PCM, PC_HW
-// port_num is a count (0-based) within that category
 struct routing_snk {

  // location within the array
@@ -98,12 +102,6 @@ struct routing_snk {
  // socket widget on the routing page
  GtkWidget *socket_widget;

-  // PC_DSP, PC_MIX, PC_PCM, or PC_HW
-  int port_category;
-
-  // 0-based count within port_category
-  int port_num;
-
  // the mixer label widgets for this sink
  GtkWidget *mixer_label_top;
  GtkWidget *mixer_label_bottom;
@@ -126,22 +124,31 @@ struct alsa_elem {
  const char *name;
  int         type;
  int         count;
+  int         index;

-  // for gain/volume elements, the dB range and step
+  // for gain/volume elements, the value range, dB type, and dB range
  int min_val;
  int max_val;
-  int min_dB;
-  int max_dB;
+  int dB_type;
+  int min_cdB;
+  int max_cdB;

-  // for the number (or translated letter; A = 1) in the item name
-  // TODO: move this to struct routing_snk?
+  // level meter labels
+  char **meter_labels;
+
+  // for routing sinks
+  int is_routing_snk;
+  int port_category;
+  int port_num;
+  int hw_type;
  int lr_num;

  // the callback functions for this ALSA control element
  GList *callbacks;

  // for simulated elements, the current state
-  int  writable;
+  int  is_writable;
+  int  is_volatile;
  long value;

  // for simulated enumerated elements, the items
@@ -155,12 +162,12 @@ struct alsa_card {
  uint32_t            pid;
  char               *serial;
  char               *name;
+  char               *fcp_socket;
  int                 best_firmware_version;
  snd_ctl_t          *handle;
  struct pollfd       pfd;
  GArray             *elems;
  struct alsa_elem   *sample_capture_elem;
-  struct alsa_elem   *level_meter_elem;
  GArray             *routing_srcs;
  GArray             *routing_snks;
  GIOChannel         *io_channel;
@@ -182,10 +189,9 @@ struct alsa_card {
  GtkWidget          *routing_dsp_out_grid;
  GtkWidget          *routing_mixer_in_grid;
  GtkWidget          *routing_mixer_out_grid;
-  GtkWidget          *meters[MAX_METERS];
-  guint               meter_gsource_timer;
  int                 has_speaker_switching;
  int                 has_talkback;
+  int                 has_fixed_mixer_inputs;
  int                 routing_out_count[PC_COUNT];
  int                 routing_in_count[PC_COUNT];
  GMenu              *routing_src_menu;
@@ -200,10 +206,14 @@ struct alsa_card {
 void fatal_alsa_error(const char *msg, int err);

 // locate elements or get information about them
-struct alsa_elem *get_elem_by_name(GArray *elems, char *name);
-struct alsa_elem *get_elem_by_prefix(GArray *elems, char *prefix);
-int get_max_elem_by_name(GArray *elems, char *prefix, char *needle);
-int is_elem_routing_snk(struct alsa_elem *elem);
+struct alsa_elem *get_elem_by_name(GArray *elems, const char *name);
+struct alsa_elem *get_elem_by_prefix(GArray *elems, const char *prefix);
+struct alsa_elem *get_elem_by_substr(GArray *elems, const char *substr);
+int get_max_elem_by_name(
+  GArray *elems,
+  const char *prefix,
+  const char *needle
+);

 // add callback to alsa_elem callback list
 void alsa_elem_add_callback(
@@ -219,6 +229,7 @@ long alsa_get_elem_value(struct alsa_elem *elem);
 int *alsa_get_elem_int_values(struct alsa_elem *elem);
 void alsa_set_elem_value(struct alsa_elem *elem, long value);
 int alsa_get_elem_writable(struct alsa_elem *elem);
+int alsa_get_elem_volatile(struct alsa_elem *elem);
 int alsa_get_elem_count(struct alsa_elem *elem);
 int alsa_get_item_count(struct alsa_elem *elem);
 char *alsa_get_item_name(struct alsa_elem *elem, int i);
@@ -226,6 +237,10 @@ char *alsa_get_item_name(struct alsa_elem *elem, int i);
 // add to alsa_cards array
 struct alsa_card *card_create(int card_num);

+// parse elements (used by alsa-sim.c)
+void alsa_set_lr_nums(struct alsa_card *card);
+void alsa_get_routing_controls(struct alsa_card *card);
+
 // init
 void alsa_init(void);

--- a/src/const.h
+++ b/src/const.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
@@ -7,7 +7,7 @@
 #define MAX_MIX_OUT 12

 // maximum number of mux inputs
-#define MAX_MUX_IN 25
+#define MAX_MUX_IN 42

 // maximum number of meters
-#define MAX_METERS 65
+#define MAX_METERS 92
--- a/src/db.c
+++ b/src/db.c
@@ -0,0 +1,83 @@
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <alsa/asoundlib.h>
+#include <math.h>
+
+static double db_to_linear(double db) {
+  if (db <= SND_CTL_TLV_DB_GAIN_MUTE)
+    return 0.0;
+  return pow(10.0, db / 20.0);
+}
+
+static double linear_to_db(double linear) {
+  if (linear <= 0.0)
+    return SND_CTL_TLV_DB_GAIN_MUTE;
+  return 20.0 * log10(linear);
+}
+
+int cdb_to_linear_value(
+  int cdb, int min_val, int max_val, int min_cdb, int max_cdb
+) {
+  if (cdb <= min_cdb)
+    return min_val;
+  if (cdb >= max_cdb)
+    return max_val;
+
+  // Convert centidB to dB
+  double db = (double)cdb / 100.0;
+  double max_db = (double)max_cdb / 100.0;
+
+  // Convert dB relative to max_db to linear scale 0.0-1.0
+  double linear = db_to_linear(db - max_db);
+
+  // Scale to full ALSA range
+  double scaled = linear * (double)max_val;
+  int value = (int)round(scaled);
+  if (value < min_val)
+    return min_val;
+  if (value > max_val)
+    return max_val;
+  return value;
+}
+
+int linear_value_to_cdb(
+  int value, int min_val, int max_val, int min_cdb, int max_cdb
+) {
+  if (value <= min_val)
+    return min_cdb;
+  if (value >= max_val)
+    return max_cdb;
+
+  // Convert to 0.0-1.0 linear scale
+  double linear = (double)value / (double)max_val;
+  double max_db = (double)max_cdb / 100.0;
+
+  // Convert to dB relative to max_db and back to centidB
+  int cdb = (int)round((linear_to_db(linear) + max_db) * 100.0);
+  if (cdb < min_cdb)
+    return min_cdb;
+  if (cdb > max_cdb)
+    return max_cdb;
+  return cdb;
+}
+
+double linear_value_to_db(
+  int value, int min_val, int max_val, int min_db, int max_db
+) {
+  if (value <= min_val)
+    return min_db;
+  if (value >= max_val)
+    return max_db;
+
+  // Convert to 0.0-1.0 linear scale
+  double linear = (double)value / (double)max_val;
+
+  // Convert to dB relative to max_db
+  double db = linear_to_db(linear) + max_db;
+  if (db < min_db)
+    return min_db;
+  if (db > max_db)
+    return max_db;
+  return db;
+}
--- a/src/db.h
+++ b/src/db.h
@@ -0,0 +1,16 @@
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#pragma once
+
+int cdb_to_linear_value(
+  int cdb, int min_val, int max_val, int min_cdb, int max_cdb
+);
+
+int linear_value_to_cdb(
+  int value, int min_val, int max_val, int min_cdb, int max_cdb
+);
+
+double linear_value_to_db(
+  int value, int min_val, int max_val, int min_db, int max_db
+);
--- a/src/device-reset-config.c
+++ b/src/device-reset-config.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <gtk/gtk.h>
--- a/src/device-reset-config.h
+++ b/src/device-reset-config.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/device-update-firmware.c
+++ b/src/device-update-firmware.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <gtk/gtk.h>
--- a/src/device-update-firmware.h
+++ b/src/device-update-firmware.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/error.c
+++ b/src/error.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "error.h"
--- a/src/error.h
+++ b/src/error.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/file.c
+++ b/src/file.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "alsa.h"
@@ -14,9 +14,15 @@ static void run_alsactl(
 ) {
  GtkWindow *w = GTK_WINDOW(card->window_main);

+  gchar *alsactl_path = g_find_program_in_path("alsactl");
+
+  if (!alsactl_path)
+    alsactl_path = g_strdup("/usr/sbin/alsactl");
+
  gchar *argv[] = {
-    "/usr/sbin/alsactl", cmd, card->device, "-f", fn, NULL
+    alsactl_path, cmd, card->device, "-f", fn, NULL
  };
+
  gchar  *stdout;
  gchar  *stderr;
  gint    exit_status;
@@ -52,6 +58,7 @@ static void run_alsactl(
  g_free(error_message);

 done:
+  g_free(alsactl_path);
  g_free(stdout);
  g_free(stderr);
  if (error)
--- a/src/file.h
+++ b/src/file.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <gtk/gtk.h>
--- a/src/gtkdial.c
+++ b/src/gtkdial.c
@@ -1,5 +1,5 @@
 // SPDX-FileCopyrightText: 2021 Stiliyan Varbanov <https://www.fiverr.com/stilvar>
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: LGPL-3.0-or-later

 /*
@@ -17,10 +17,13 @@
 #include <math.h>

 #include "gtkdial.h"
+#include "db.h"

 #define DIAL_MIN_WIDTH 50
 #define DIAL_MAX_WIDTH 70

+#define HISTORY_COUNT 50
+
 static int set_value(GtkDial *dial, double newval);

 static void gtk_dial_set_property(
@@ -88,8 +91,10 @@ enum {
  PROP_ROUND_DIGITS,
  PROP_ZERO_DB,
  PROP_OFF_DB,
+  PROP_IS_LINEAR,
  PROP_TAPER,
  PROP_CAN_CONTROL,
+  PROP_PEAK_HOLD,
  LAST_PROP
 };

@@ -115,8 +120,10 @@ struct _GtkDial {
  int round_digits;
  double zero_db;
  double off_db;
+  gboolean is_linear;
  int taper;
  gboolean can_control;
+  int peak_hold;

  int properties_updated;

@@ -150,11 +157,24 @@ struct _GtkDial {
  cairo_pattern_t *fill_pattern[2][2];
  cairo_pattern_t *outline_pattern[2];

+  // pango resources for displaying the peak value
+  PangoLayout *peak_layout;
+  PangoFontDescription *peak_font_desc;
+
  // variables derived from the dial value
  double valp;
  double angle;
  double slider_cx;
  double slider_cy;
+
+  // same for the peak angle
+  double peak_angle;
+
+  // value history for displaying peak
+  double hist_values[HISTORY_COUNT];
+  long long hist_time[HISTORY_COUNT];
+  double current_peak;
+  int hist_head, hist_tail, hist_count;
 };

 G_DEFINE_TYPE(GtkDial, gtk_dial, GTK_TYPE_WIDGET)
@@ -176,6 +196,17 @@ static void dial_measure(
                                      "move-slider", \
                                      "(i)", scroll)

+long long current_time = 0;
+
+void gtk_dial_peak_tick(void) {
+  struct timespec ts;
+
+  if (clock_gettime(CLOCK_BOOTTIME, &ts) < 0)
+    return;
+
+  current_time = ts.tv_sec * 1000 + ts.tv_nsec / 1000000;
+}
+
 // BEGIN SECTION HELPERS

 #define TOTAL_ROTATION_DEGREES 290
@@ -226,6 +257,13 @@ static double calc_taper(GtkDial *dial, double val) {
  double mn = gtk_adjustment_get_lower(dial->adj);
  double mx = gtk_adjustment_get_upper(dial->adj);
  double off_db = gtk_dial_get_off_db(dial);
+  gboolean is_linear = gtk_dial_get_is_linear(dial);
+
+  if (is_linear) {
+    val = linear_value_to_cdb(val, mn, mx, -8000, 1200) / 100.0;
+    mn = -60;
+    mx = 12;
+  }

  // if off_db is set, then values below it are considered as
  // almost-silence, so we clamp them to 0.01
@@ -381,6 +419,21 @@ static int update_dial_properties(GtkDial *dial) {
    dial->outline_pattern[dim] = pat;
  }

+  // init pango layout for peak value
+  if (dial->peak_layout)
+    g_object_unref(dial->peak_layout);
+  if (dial->peak_font_desc)
+    pango_font_description_free(dial->peak_font_desc);
+
+  PangoContext *context = gtk_widget_create_pango_context(GTK_WIDGET(dial));
+  dial->peak_layout = pango_layout_new(context);
+  dial->peak_font_desc = pango_context_get_font_description(context);
+  int size = pango_font_description_get_size(dial->peak_font_desc) * 0.6;
+  dial->peak_font_desc = pango_font_description_copy(dial->peak_font_desc);
+  pango_font_description_set_size(dial->peak_font_desc, size);
+  pango_layout_set_font_description(dial->peak_layout, dial->peak_font_desc);
+  g_object_unref(context);
+
  // calculate level meter breakpoint angles
  if (dial->level_breakpoint_angles)
    free(dial->level_breakpoint_angles);
@@ -404,6 +457,12 @@ static void update_dial_values(GtkDial *dial) {
  dial->angle = calc_val(dial->valp, ANGLE_START, ANGLE_END);
  dial->slider_cx = cos(dial->angle) * dial->slider_radius + dial->cx;
  dial->slider_cy = sin(dial->angle) * dial->slider_radius + dial->cy;
+
+  if (!dial->peak_hold)
+    return;
+
+  double peak_valp = calc_taper(dial, dial->current_peak);
+  dial->peak_angle = calc_val(peak_valp, ANGLE_START, ANGLE_END);
 }

 static double pdist2(double x1, double y1, double x2, double y2) {
@@ -502,6 +561,19 @@ static void gtk_dial_class_init(GtkDialClass *klass) {
    G_PARAM_READWRITE | G_PARAM_CONSTRUCT
  );

+  /**
+   * GtkDial:is_linear: (attributes org.gtk.Method.get=gtk_dial_get_is_linear org.gtk.Method.set=gtk_dial_set_is_linear)
+   *
+   * Whether the dial values are linear or dB.
+   */
+  properties[PROP_IS_LINEAR] = g_param_spec_boolean(
+    "is_linear",
+    "IsLinear",
+    "Whether the dial values are linear or dB",
+    FALSE,
+    G_PARAM_READWRITE | G_PARAM_CONSTRUCT
+  );
+
  /**
   * GtkDial:taper: (attributes org.gtk.Method.get=gtk_dial_get_taper org.gtk.Method.set=gtk_dial_set_taper)
   *
@@ -530,6 +602,20 @@ static void gtk_dial_class_init(GtkDialClass *klass) {
    G_PARAM_READWRITE | G_PARAM_CONSTRUCT
  );

+  /**
+   * GtkDial:peak-hold: (attributes org.gtk.Method.get=gtk_dial_get_peak_hold org.gtk.Method.set=gtk_dial_set_peak_hold)
+   *
+   * The number of milliseconds to hold the peak value.
+   */
+  properties[PROP_PEAK_HOLD] = g_param_spec_int(
+    "peak-hold",
+    "PeakHold",
+    "The number of milliseconds to hold the peak value",
+    0, 1000,
+    0,
+    G_PARAM_READWRITE | G_PARAM_CONSTRUCT
+  );
+
  g_object_class_install_properties(g_class, LAST_PROP, properties);

  /**
@@ -648,6 +734,11 @@ static void gtk_dial_init(GtkDial *dial) {
  g_signal_connect(
    dial, "notify::sensitive", G_CALLBACK(gtk_dial_notify_sensitive_cb), dial
  );
+
+  dial->current_peak = -INFINITY;
+  dial->hist_head = 0;
+  dial->hist_tail = 0;
+  dial->hist_count = 0;
 }

 static void dial_measure(
@@ -686,6 +777,70 @@ static void cairo_set_source_rgba_dim(
    cairo_set_source_rgba(cr, r, g, b, a);
 }

+static void draw_peak(GtkDial *dial, cairo_t *cr, double radius) {
+
+  double angle_start = dial->peak_angle - M_PI / 180;
+  if (angle_start < ANGLE_START)
+    return;
+
+  // determine the colour of the peak
+  int count = dial->level_breakpoints_count;
+
+  // if there are no colours, don't draw the peak
+  if (!count)
+    return;
+
+  int i;
+
+  for (i = 0; i < count - 1; i++)
+    if (dial->current_peak < dial->level_breakpoints[i + 1])
+      break;
+
+  const double *colours = &dial->level_colours[i * 3];
+
+  cairo_set_source_rgba_dim(
+    cr, colours[0], colours[1], colours[2], 0.5, dial->dim
+  );
+  cairo_set_line_width(cr, 2);
+  cairo_arc(cr, dial->cx, dial->cy, radius, ANGLE_START, dial->peak_angle);
+  cairo_stroke(cr);
+
+  cairo_set_source_rgba_dim(
+    cr, colours[0], colours[1], colours[2], 1, dial->dim
+  );
+  cairo_set_line_width(cr, 4);
+  cairo_arc(cr, dial->cx, dial->cy, radius, angle_start, dial->peak_angle);
+  cairo_stroke(cr);
+}
+
+static void show_peak_value(GtkDial *dial, cairo_t *cr) {
+  double value = round(dial->current_peak);
+
+  if (value <= gtk_adjustment_get_lower(dial->adj))
+    return;
+
+  char s[20];
+  char *p = s;
+  if (value < 0)
+    p += sprintf(p, "−");
+  snprintf(p, 10, "%.0f", fabs(value));
+
+  pango_layout_set_text(dial->peak_layout, s, -1);
+
+  int width, height;
+  pango_layout_get_pixel_size(dial->peak_layout, &width, &height);
+
+  cairo_set_source_rgba_dim(cr, 1, 1, 1, 0.5, dial->dim);
+
+  cairo_move_to(
+    cr,
+    dial->cx - width / 2 - 1,
+    dial->cy - height / 2
+  );
+
+  pango_cairo_show_layout(cr, dial->peak_layout);
+}
+
 static void draw_slider(
  GtkDial *dial,
  cairo_t *cr,
@@ -781,6 +936,10 @@ static void dial_snapshot(GtkWidget *widget, GtkSnapshot *snapshot) {
    draw_slider(dial, cr, dial->slider_radius, 6, 0.3);
  }

+  // peak hold
+  if (dial->peak_hold)
+    draw_peak(dial, cr, dial->slider_radius);
+
  // draw line to zero db
  double zero_db = gtk_dial_get_zero_db(dial);
  if (zero_db != -G_MAXDOUBLE) {
@@ -821,6 +980,10 @@ static void dial_snapshot(GtkWidget *widget, GtkSnapshot *snapshot) {
  cairo_set_line_width(cr, 2);
  cairo_stroke(cr);

+  // show the peak value
+  if (dial->peak_hold)
+    show_peak_value(dial, cr);
+
  // if focussed
  if (has_focus) {
    cairo_set_source_rgba(cr, 1, 0.125, 0.125, 0.5);
@@ -897,12 +1060,18 @@ static void gtk_dial_set_property(
    case PROP_OFF_DB:
      gtk_dial_set_off_db(dial, g_value_get_double(value));
      break;
+    case PROP_IS_LINEAR:
+      gtk_dial_set_is_linear(dial, g_value_get_boolean(value));
+      break;
    case PROP_TAPER:
      gtk_dial_set_taper(dial, g_value_get_int(value));
      break;
    case PROP_CAN_CONTROL:
      gtk_dial_set_can_control(dial, g_value_get_boolean(value));
      break;
+    case PROP_PEAK_HOLD:
+      gtk_dial_set_peak_hold(dial, g_value_get_int(value));
+      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
      break;
@@ -930,12 +1099,18 @@ static void gtk_dial_get_property(
    case PROP_OFF_DB:
      g_value_set_double(value, dial->off_db);
      break;
+    case PROP_IS_LINEAR:
+      g_value_set_boolean(value, dial->is_linear);
+      break;
    case PROP_TAPER:
      g_value_set_int(value, dial->taper);
      break;
    case PROP_CAN_CONTROL:
      g_value_set_boolean(value, dial->can_control);
      break;
+    case PROP_PEAK_HOLD:
+      g_value_set_int(value, dial->peak_hold);
+      break;
    default:
      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
      break;
@@ -978,6 +1153,15 @@ double gtk_dial_get_off_db(GtkDial *dial) {
  return dial->off_db;
 }

+void gtk_dial_set_is_linear(GtkDial *dial, gboolean is_linear) {
+  dial->is_linear = is_linear;
+  dial->properties_updated = 1;
+}
+
+gboolean gtk_dial_get_is_linear(GtkDial *dial) {
+  return dial->is_linear;
+}
+
 void gtk_dial_set_taper(GtkDial *dial, int taper) {
  dial->taper = taper;
  dial->properties_updated = 1;
@@ -1044,6 +1228,14 @@ void gtk_dial_set_level_meter_colours(
  dial->properties_updated = 1;
 }

+void gtk_dial_set_peak_hold(GtkDial *dial, int peak_hold) {
+  dial->peak_hold = peak_hold;
+}
+
+int gtk_dial_get_peak_hold(GtkDial *dial) {
+  return dial->peak_hold;
+}
+
 void gtk_dial_set_adjustment(GtkDial *dial, GtkAdjustment *adj) {
  if (!(adj == NULL || GTK_IS_ADJUSTMENT(adj)))
    return;
@@ -1059,6 +1251,46 @@ GtkAdjustment *gtk_dial_get_adjustment(GtkDial *dial) {
  return dial->adj;
 }

+static void gtk_dial_add_hist_value(GtkDial *dial, double value) {
+
+  int need_peak_update = 0;
+
+  // remove the oldest value(s) if they are too old or if the history
+  // is full
+  while (dial->hist_count > 0 &&
+         (dial->hist_time[dial->hist_head] < current_time - dial->peak_hold ||
+          dial->hist_count == HISTORY_COUNT)) {
+
+    // check if the value removed is the current peak
+    if (dial->hist_values[dial->hist_head] >= dial->current_peak)
+      need_peak_update = 1;
+
+    // move the head forward
+    dial->hist_head = (dial->hist_head + 1) % HISTORY_COUNT;
+    dial->hist_count--;
+  }
+
+  // recalculate the peak if needed
+  if (need_peak_update) {
+    dial->current_peak = -INFINITY;
+    for (int i = dial->hist_head;
+         i != dial->hist_tail;
+         i = (i + 1) % HISTORY_COUNT)
+      if (dial->hist_values[i] > dial->current_peak)
+        dial->current_peak = dial->hist_values[i];
+  }
+
+  // add the new value
+  dial->hist_values[dial->hist_tail] = value;
+  dial->hist_time[dial->hist_tail] = current_time;
+  dial->hist_tail = (dial->hist_tail + 1) % HISTORY_COUNT;
+  dial->hist_count++;
+
+  // update the peak if needed
+  if (value > dial->current_peak)
+    dial->current_peak = value;
+}
+
 static int set_value(GtkDial *dial, double newval) {
  if (dial->round_digits >= 0) {
    double power;
@@ -1079,7 +1311,10 @@ static int set_value(GtkDial *dial, double newval) {

  double oldval = gtk_adjustment_get_value(dial->adj);

-  if (oldval == newval)
+  double old_peak = dial->current_peak;
+  gtk_dial_add_hist_value(dial, newval);
+
+  if (oldval == newval && old_peak == dial->current_peak)
    return 0;

  gtk_adjustment_set_value(dial->adj, newval);
@@ -1088,35 +1323,44 @@ static int set_value(GtkDial *dial, double newval) {
  double old_valp = dial->valp;
  update_dial_values(dial);

-  return old_valp != dial->valp;
+  return old_valp != dial->valp || old_peak != dial->current_peak;
+}
+
+static double do_step(GtkDial *dial, double step_amount) {
+  double mn = gtk_adjustment_get_lower(dial->adj);
+  double mx = gtk_adjustment_get_upper(dial->adj);
+  double newval = gtk_adjustment_get_value(dial->adj);
+  double step = gtk_adjustment_get_step_increment(dial->adj);
+
+  if (gtk_dial_get_is_linear(dial)) {
+    double db_val = linear_value_to_cdb(newval, mn, mx, -8000, 1200) / 100.0;
+    db_val = round(db_val / step) * step + step_amount;
+
+    newval = cdb_to_linear_value(db_val * 100.0, mn, mx, -8000, 1200);
+    if (newval == gtk_adjustment_get_value(dial->adj)) {
+      newval = CLAMP(newval + (step_amount > 0 ? 1 : -1), mn, mx);
+    }
+  } else {
+    newval += step_amount;
+  }
+
+  return newval;
 }

 static void step_back(GtkDial *dial) {
-  double newval;
-
-  newval = gtk_adjustment_get_value(dial->adj) - gtk_adjustment_get_step_increment(dial->adj);
-  set_value(dial, newval);
+  set_value(dial, do_step(dial, -gtk_adjustment_get_step_increment(dial->adj)));
 }

 static void step_forward(GtkDial *dial) {
-  double newval;
-
-  newval = gtk_adjustment_get_value(dial->adj) + gtk_adjustment_get_step_increment(dial->adj);
-  set_value(dial, newval);
+  set_value(dial, do_step(dial, gtk_adjustment_get_step_increment(dial->adj)));
 }

 static void page_back(GtkDial *dial) {
-  double newval;
-
-  newval = gtk_adjustment_get_value(dial->adj) - gtk_adjustment_get_page_increment(dial->adj);
-  set_value(dial, newval);
+  set_value(dial, do_step(dial, -gtk_adjustment_get_page_increment(dial->adj)));
 }

 static void page_forward(GtkDial *dial) {
-  double newval;
-
-  newval = gtk_adjustment_get_value(dial->adj) + gtk_adjustment_get_page_increment(dial->adj);
-  set_value(dial, newval);
+  set_value(dial, do_step(dial, gtk_adjustment_get_page_increment(dial->adj)));
 }

 static void scroll_begin(GtkDial *dial) {
@@ -1246,20 +1490,56 @@ static void gtk_dial_drag_gesture_update(
  double          offset_y,
  GtkDial        *dial
 ) {
-  double start_x, start_y;
+  double mn = gtk_adjustment_get_lower(dial->adj);
+  double mx = gtk_adjustment_get_upper(dial->adj);
+  gboolean is_linear = gtk_dial_get_is_linear(dial);

-  gtk_gesture_drag_get_start_point(gesture, &start_x, &start_y);
+  double valp;

-  double valp = dial->dvalp - DRAG_FACTOR * (offset_y / dial->h);
-  valp = CLAMP(valp, 0.0, 1.0);
+  // add a 1px deadband to prevent double-click with zero mouse
+  // movement from changing the value from the toggled -inf/0dB value
+  // (sometimes we see an offset_y value that rounds to +/- 1 which
+  // causes the value to change after the double-click has set the
+  // value)
+  if (offset_y < -1) {
+    offset_y += 1;
+  } else if (offset_y < 1) {
+    offset_y = 0;
+  } else {
+    offset_y -= 1;
+  }

-  double val = calc_val(
-    valp,
-    gtk_adjustment_get_lower(dial->adj),
-    gtk_adjustment_get_upper(dial->adj)
-  );
+  if (is_linear) {
+    double step = gtk_adjustment_get_step_increment(dial->adj);
+
+    // Convert initial value from linear to dB space
+    double db_val = linear_value_to_cdb(
+      calc_val(dial->dvalp, mn, mx),
+      mn, mx,
+      -8000, 1200
+    ) / 100.0;
+
+    // Adjust in dB space
+    db_val -= 30.0 * DRAG_FACTOR * (offset_y / dial->h);
+
+    // Round
+    db_val = round(db_val / step) * step;
+
+    // Convert back to linear space and normalise
+    double val = cdb_to_linear_value(
+      db_val * 100.0,
+      mn, mx,
+      -8000, 1200
+    );
+
+    valp = calc_valp(val, mn, mx);
+  } else {
+    valp = dial->dvalp - DRAG_FACTOR * (offset_y / dial->h);
+    valp = CLAMP(valp, 0.0, 1.0);
+  }
+
+  set_value(dial, calc_val(valp, mn, mx));

-  set_value(dial, val);
  gtk_widget_queue_draw(GTK_WIDGET(dial));
 }

@@ -1322,7 +1602,7 @@ static gboolean gtk_dial_scroll_controller_scroll(

  double step = -gtk_adjustment_get_step_increment(dial->adj) * delta;

-  set_value(dial, gtk_adjustment_get_value(dial->adj) + step);
+  set_value(dial, do_step(dial, step));
  gtk_widget_queue_draw(GTK_WIDGET(dial));

  return GDK_EVENT_STOP;
@@ -1348,6 +1628,11 @@ void gtk_dial_dispose(GObject *o) {
    if (dial->outline_pattern[dim])
      cairo_pattern_destroy(dial->outline_pattern[dim]);

+  if (dial->peak_layout)
+    g_object_unref(dial->peak_layout);
+  if (dial->peak_font_desc)
+    pango_font_description_free(dial->peak_font_desc);
+
  g_object_unref(dial->adj);
  dial->adj = NULL;
  G_OBJECT_CLASS(gtk_dial_parent_class)->dispose(o);
--- a/src/gtkdial.h
+++ b/src/gtkdial.h
@@ -1,5 +1,5 @@
 // SPDX-FileCopyrightText: 2021 Stiliyan Varbanov <https://www.fiverr.com/stilvar>
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: LGPL-3.0-or-later

 /*
@@ -68,6 +68,9 @@ double gtk_dial_get_zero_db(GtkDial *dial);
 void gtk_dial_set_off_db(GtkDial *dial, double off_db);
 double gtk_dial_get_off_db(GtkDial *dial);

+void gtk_dial_set_is_linear(GtkDial *dial, gboolean is_linear);
+gboolean gtk_dial_get_is_linear(GtkDial *dial);
+
 // taper functions
 enum {
  GTK_DIAL_TAPER_LINEAR,
@@ -94,6 +97,17 @@ void gtk_dial_set_level_meter_colours(
  int           count
 );

+void gtk_dial_set_peak_hold(GtkDial *dial, int peak_hold);
+int gtk_dial_get_peak_hold(GtkDial *dial);
+void gtk_dial_peak_tick(void);
+
+int cdb_to_linear_value(
+  int db, int min_val, int max_val, int min_db, int max_db
+);
+int linear_value_to_cdb(
+  int value, int min_val, int max_val, int min_db, int max_db
+);
+
 G_END_DECLS

 #endif
--- a/src/gtkhelper.c
+++ b/src/gtkhelper.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "gtkhelper.h"
--- a/src/gtkhelper.h
+++ b/src/gtkhelper.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/hardware.c
+++ b/src/hardware.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <stddef.h>
--- a/src/hardware.h
+++ b/src/hardware.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 // Supported devices
--- a/src/iface-mixer.c
+++ b/src/iface-mixer.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "gtkhelper.h"
@@ -26,8 +26,12 @@ static void add_clock_source_control(

  struct alsa_elem *clock_source = get_elem_by_prefix(elems, "Clock Source");

-  if (!clock_source)
-    return;
+  if (!clock_source) {
+    clock_source = get_elem_by_substr(elems, "Sync Clock Source");
+
+    if (!clock_source)
+      return;
+  }

  GtkWidget *b = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
  gtk_widget_set_tooltip_text(
@@ -55,8 +59,11 @@ static void add_sync_status_control(

  struct alsa_elem *sync_status = get_elem_by_name(elems, "Sync Status");

-  if (!sync_status)
-    return;
+  if (!sync_status) {
+    sync_status = get_elem_by_name(elems, "Sample Clock Sync Status");
+    if (!sync_status)
+      return;
+  }

  GtkWidget *b = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
  if (get_elem_by_prefix(elems, "Clock Source")) {
@@ -139,7 +146,7 @@ static void add_sample_rate_control(
  gtk_box_append(GTK_BOX(b), w);
 }

-static void add_speaker_switching_controls(
+static void add_speaker_switching_controls_enum(
  struct alsa_card *card,
  GtkWidget        *global_controls
 ) {
@@ -167,7 +174,43 @@ static void add_speaker_switching_controls(
  gtk_box_append(GTK_BOX(global_controls), w);
 }

-static void add_talkback_controls(
+static void add_speaker_switching_controls_switches(
+  struct alsa_card *card,
+  GtkWidget        *global_controls
+) {
+  GArray *elems = card->elems;
+
+  struct alsa_elem *enable = get_elem_by_name(
+    elems, "Speaker Switching Playback Switch"
+  );
+  struct alsa_elem *alt = get_elem_by_name(
+    elems, "Speaker Switching Alt Playback Switch"
+  );
+
+  if (!enable || !alt)
+    return;
+
+  GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
+  gtk_widget_set_tooltip_text(
+    box,
+    "Speaker Switching lets you swap between two pairs of "
+    "monitoring speakers very easily."
+  );
+
+  GtkWidget *l = gtk_label_new("Speaker Switching");
+  GtkWidget *w1 = make_boolean_alsa_elem(enable, "Off", "On");
+  GtkWidget *w2 = make_boolean_alsa_elem(alt, "Main", "Alt");
+
+  gtk_widget_add_css_class(w1, "speaker-switching-enable");
+  gtk_widget_add_css_class(w2, "speaker-switching-alt");
+
+  gtk_box_append(GTK_BOX(box), l);
+  gtk_box_append(GTK_BOX(box), w1);
+  gtk_box_append(GTK_BOX(box), w2);
+  gtk_box_append(GTK_BOX(global_controls), box);
+}
+
+static void add_talkback_controls_enum(
  struct alsa_card *card,
  GtkWidget        *global_controls
 ) {
@@ -196,6 +239,43 @@ static void add_talkback_controls(
  gtk_box_append(GTK_BOX(global_controls), w);
 }

+static void add_talkback_controls_switches(
+  struct alsa_card *card,
+  GtkWidget        *global_controls
+) {
+  GArray *elems = card->elems;
+
+  struct alsa_elem *enable = get_elem_by_name(
+    elems, "Talkback Enable Playback Switch"
+  );
+  struct alsa_elem *talk = get_elem_by_name(
+    elems, "Talk Playback Switch"
+  );
+
+  if (!enable || !talk)
+    return;
+
+  GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
+  gtk_widget_set_tooltip_text(
+    box,
+    "Talkback lets you add another channel (usually the talkback "
+    "mic) to a mix with a button push, usually to talk to "
+    "musicians, and without using an additional mic channel."
+  );
+
+  GtkWidget *l = gtk_label_new("Talkback");
+  GtkWidget *w1 = make_boolean_alsa_elem(enable, "Disabled", "Enabled");
+  GtkWidget *w2 = make_boolean_alsa_elem(talk, "Talk", "Talk");
+
+  gtk_widget_add_css_class(w1, "talkback-enable");
+  gtk_widget_add_css_class(w2, "talk");
+
+  gtk_box_append(GTK_BOX(box), l);
+  gtk_box_append(GTK_BOX(box), w1);
+  gtk_box_append(GTK_BOX(box), w2);
+  gtk_box_append(GTK_BOX(global_controls), box);
+}
+
 static GtkWidget *create_global_box(GtkWidget *grid, int *x, int orient) {
  GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 5);
  gtk_widget_set_vexpand(box, TRUE);
@@ -253,8 +333,13 @@ static void create_input_link_control(

  int from, to;
  get_two_num_from_string(elem->name, &from, &to);
+
+  // skip even numbers
+  if (!(from % 2))
+    return;
+
  if (to == -1)
-    to = from;
+    to = from + 1;

  gtk_grid_attach(GTK_GRID(grid), w, from - 1, current_row, to - from + 1, 1);
 }
@@ -420,6 +505,25 @@ static void create_input_pad_control(
  gtk_grid_attach(GTK_GRID(grid), w, column_num, current_row, 1, 1);
 }

+static void create_input_gain_switch_control(
+  struct alsa_elem *elem,
+  GtkWidget        *grid,
+  int               current_row,
+  int               column_num
+) {
+  GtkWidget *w = make_boolean_alsa_elem(elem, "Gain", NULL);
+  gtk_widget_add_css_class(w, "gain-switch");
+  gtk_widget_set_hexpand(w, TRUE);
+  gtk_widget_set_tooltip_text(
+    w,
+    "Enabling Gain switches from Low gain input (0dBFS = +16dBu)\n"
+    "to High gain input (0dBFS = −10dBV, approx −6dBu)."
+  );
+
+  // ignore current_row, always put it in the first row
+  gtk_grid_attach(GTK_GRID(grid), w, column_num, 1, 1, 1);
+}
+
 static void create_input_phantom_control(
  struct alsa_elem *elem,
  GtkWidget        *grid,
@@ -476,13 +580,11 @@ static void create_input_controls_by_type(
 static void create_input_controls(
  struct alsa_card *card,
  GtkWidget        *top,
-  int              *x
+  int              *x,
+  int              input_count
 ) {
  GArray *elems = card->elems;

-  // find how many inputs have switches
-  int input_count = get_max_elem_by_name(elems, "Line", "Capture Switch");
-
  // Only the 18i20 Gen 2 has no input controls
  if (!input_count)
    return;
@@ -522,6 +624,25 @@ static void create_input_controls(

  int current_row = 1;

+  // 4th Gen Solo, put the Phantom Power control above the Air control
+  if (get_elem_by_name(elems, "Direct Monitor Playback Switch")) {
+    create_input_controls_by_type(
+      elems, input_grid, &current_row,
+      "Level Capture Enum", create_input_level_control
+    );
+    create_input_controls_by_type(
+      elems, input_grid, &current_row,
+      "Phantom Power Capture Switch", create_input_phantom_control
+    );
+    create_input_controls_by_type(
+      elems, input_grid, &current_row,
+      "Air Capture Enum", create_input_air_enum_control
+    );
+
+    (*x)++;
+    return;
+  }
+
  create_input_select_control(elems, input_grid, &current_row);

  create_input_controls_by_type(
@@ -548,6 +669,10 @@ static void create_input_controls(
    elems, input_grid, &current_row,
    "Level Capture Enum", create_input_level_control
  );
+  create_input_controls_by_type(
+    elems, input_grid, &current_row,
+    "Impedance Switch", create_input_level_control
+  );
  create_input_controls_by_type(
    elems, input_grid, &current_row,
    "Air Capture Switch", create_input_air_switch_control
@@ -572,6 +697,14 @@ static void create_input_controls(
    elems, input_grid, &current_row,
    "Pad Capture Switch", create_input_pad_control
  );
+  create_input_controls_by_type(
+    elems, input_grid, &current_row,
+    "Pad Switch", create_input_pad_control
+  );
+  create_input_controls_by_type(
+    elems, input_grid, &current_row,
+    "Gain Switch", create_input_gain_switch_control
+  );
  create_input_controls_by_type(
    elems, input_grid, &current_row,
    "Phantom Power Capture Switch", create_input_phantom_control
@@ -585,7 +718,8 @@ static void create_output_controls(
  GtkWidget        *top,
  int              *x,
  int              y,
-  int              x_span
+  int              x_span,
+  int              output_count
 ) {
  GArray *elems = card->elems;

@@ -605,8 +739,6 @@ static void create_output_controls(

  gtk_grid_attach(GTK_GRID(top), box, *x, y, x_span, 1);

-  int output_count = get_max_elem_by_name(elems, "Line", "Playback Volume");
-
  /* 4th Gen Solo/2i2 */
  if (get_elem_by_prefix(elems, "Direct Monitor Playback")) {
    struct alsa_elem *elem;
@@ -651,8 +783,12 @@ static void create_output_controls(
    return;
  }

-  int has_hw_vol = !!get_elem_by_name(elems, "Master HW Playback Volume");
-  int line_1_col = has_hw_vol;
+  int has_sw_hw_ctrls =
+    !!get_elem_by_substr(elems, "Volume Control Playback Enum");
+  int line_1_col =
+    has_sw_hw_ctrls ||
+    get_elem_by_name(elems, "Mute Playback Switch") ||
+    get_elem_by_name(elems, "Master Playback Switch");

  for (int i = 0; i < output_count; i++) {
    char s[20];
@@ -669,21 +805,31 @@ static void create_output_controls(
    if (!elem->card)
      continue;

-    int line_num = get_num_from_string(elem->name);
-
    // output controls
-    if (strncmp(elem->name, "Line", 4) == 0) {
+
+    // Gen 1 master output control
+    if (strcmp(elem->name, "Master Playback Volume") == 0) {
+      GtkWidget *l = gtk_label_new("Master");
+      gtk_grid_attach(GTK_GRID(output_grid), l, 0, 0, 1, 1);
+      w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG, 0);
+      gtk_widget_set_tooltip_text(w, "Master Volume Control");
+      gtk_grid_attach(GTK_GRID(output_grid), w, 0, 1, 1, 1);
+
+    } else if (strncmp(elem->name, "Line", 4) == 0 ||
+               strncmp(elem->name, "Master", 4) == 0 ||
+               strncmp(elem->name, "Analogue", 8) == 0) {
+
      if (strstr(elem->name, "Playback Volume")) {
        w = make_gain_alsa_elem(elem, 1, WIDGET_GAIN_TAPER_LOG, 1);
        gtk_grid_attach(
-          GTK_GRID(output_grid), w, line_num - 1 + line_1_col, 1, 1, 1
+          GTK_GRID(output_grid), w, elem->lr_num - 1 + line_1_col, 1, 1, 1
        );
-      } else if (strstr(elem->name, "Mute Playback Switch")) {
+      } else if (strstr(elem->name, "Playback Switch")) {
        w = make_boolean_alsa_elem(
          elem, "*audio-volume-high", "*audio-volume-muted"
        );
        gtk_widget_add_css_class(w, "mute");
-        if (has_hw_vol) {
+        if (has_sw_hw_ctrls) {
          gtk_widget_set_tooltip_text(
            w,
            "Mute (only available when under software control)"
@@ -692,7 +838,7 @@ static void create_output_controls(
          gtk_widget_set_tooltip_text(w, "Mute");
        }
        gtk_grid_attach(
-          GTK_GRID(output_grid), w, line_num - 1 + line_1_col, 2, 1, 1
+          GTK_GRID(output_grid), w, elem->lr_num - 1 + line_1_col, 2, 1, 1
        );
      } else if (strstr(elem->name, "Volume Control Playback Enum")) {
        w = make_boolean_alsa_elem(elem, "SW", "HW");
@@ -703,7 +849,7 @@ static void create_output_controls(
          "volume for this analogue output."
        );
        gtk_grid_attach(
-          GTK_GRID(output_grid), w, line_num - 1 + line_1_col, 3, 1, 1
+          GTK_GRID(output_grid), w, elem->lr_num - 1 + line_1_col, 3, 1, 1
        );
      }

@@ -785,8 +931,10 @@ static void create_global_controls(
  add_sync_status_control(card, column[1]);
  add_power_status_control(card, column[1]);
  add_sample_rate_control(card, column[2]);
-  add_speaker_switching_controls(card, column[0]);
-  add_talkback_controls(card, column[1]);
+  add_speaker_switching_controls_enum(card, column[0]);
+  add_speaker_switching_controls_switches(card, column[0]);
+  add_talkback_controls_enum(card, column[1]);
+  add_talkback_controls_switches(card, column[1]);
 }

 static GtkWidget *create_main_window_controls(struct alsa_card *card) {
@@ -812,18 +960,28 @@ static GtkWidget *create_main_window_controls(struct alsa_card *card) {
  int input_count = get_max_elem_by_name(
    card->elems, "Line", "Capture Switch"
  );
+  if (!input_count)
+    input_count =
+      get_max_elem_by_name(card->elems, "Input", "Switch");
+
  int output_count = get_max_elem_by_name(
    card->elems, "Line", "Playback Volume"
  );
+  if (!output_count)
+    output_count =
+      get_max_elem_by_name(card->elems, "Master", "Playback Volume") * 2;
+  if (!output_count)
+    output_count =
+      get_max_elem_by_name(card->elems, "Analogue", "Playback Volume");

  create_global_controls(card, top, &x);
-  create_input_controls(card, top, &x);
+  create_input_controls(card, top, &x, input_count);

  if (input_count + output_count >= 12) {
    x = 0;
-    create_output_controls(card, top, &x, 1, 2);
+    create_output_controls(card, top, &x, 1, 2, output_count);
  } else {
-    create_output_controls(card, top, &x, 0, 1);
+    create_output_controls(card, top, &x, 0, 1, output_count);
  }

  return top;
@@ -880,9 +1038,12 @@ static void create_scrollable_window(GtkWidget *window, GtkWidget *controls) {

 GtkWidget *create_iface_mixer_main(struct alsa_card *card) {
  card->has_speaker_switching =
-    !!get_elem_by_name(card->elems, "Speaker Switching Playback Enum");
+    get_elem_by_name(card->elems, "Speaker Switching Playback Enum") ||
+    get_elem_by_name(card->elems, "Speaker Switching Playback Switch");
+
  card->has_talkback =
-    !!get_elem_by_name(card->elems, "Talkback Playback Enum");
+    get_elem_by_name(card->elems, "Talkback Playback Enum") ||
+    get_elem_by_name(card->elems, "Talkback Enable Playback Switch");

  GtkWidget *top = gtk_frame_new(NULL);
  gtk_widget_add_css_class(top, "window-frame");
--- a/src/iface-mixer.h
+++ b/src/iface-mixer.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/iface-no-mixer.c
+++ b/src/iface-no-mixer.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "gtkhelper.h"
--- a/src/iface-no-mixer.h
+++ b/src/iface-no-mixer.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/iface-none.c
+++ b/src/iface-none.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "alsa.h"
@@ -10,7 +10,7 @@ GtkWidget *create_window_iface_none(GtkApplication *app) {
  GtkWidget *box = gtk_box_new(GTK_ORIENTATION_VERTICAL, 50);
  gtk_widget_set_margin(box, 50);
  GtkWidget *picture = gtk_picture_new_for_resource(
-    "/vu/b4/alsa-scarlett-gui/icons/alsa-scarlett-gui-logo.png"
+    "/vu/b4/alsa-scarlett-gui/icons/vu.b4.alsa-scarlett-gui.png"
  );
  GtkWidget *label = gtk_label_new("No Scarlett/Clarett/Vocaster interface found.");

@@ -19,7 +19,7 @@ GtkWidget *create_window_iface_none(GtkApplication *app) {

  GtkWidget *w = gtk_application_window_new(app);
  gtk_window_set_resizable(GTK_WINDOW(w), FALSE);
-  gtk_window_set_title(GTK_WINDOW(w), "ALSA Scarlett2 Control Panel");
+  gtk_window_set_title(GTK_WINDOW(w), "ALSA Scarlett Control Panel");
  gtk_window_set_child(GTK_WINDOW(w), box);
  gtk_application_window_set_show_menubar(
    GTK_APPLICATION_WINDOW(w), TRUE
--- a/src/iface-none.h
+++ b/src/iface-none.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/iface-unknown.c
+++ b/src/iface-unknown.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "gtkhelper.h"
@@ -9,21 +9,15 @@ GtkWidget *create_iface_unknown_main(void) {
    "Sorry, I don’t recognise the controls on this card.\n\n"

    "These Focusrite models should be supported:\n"
+    "– Gen 1: 6i6/8i6/18i6/18i8/18i20\n"
    "– Gen 2: 6i6/18i8/18i20\n"
    "– Gen 3: Solo/2i2/4i4/8i6/18i8/18i20\n"
-    "– Gen 4: Solo/2i2/4i4\n"
+    "– Gen 4: Solo/2i2/4i4/16i16/18i16/18i20\n"
+    "– Vocaster One and Two\n"
    "– Clarett USB and Clarett+ 2Pre/4Pre/8Pre\n\n"

-    "Are you running a recent kernel with Scarlett2 support "
-    "enabled?\n\n"
-
-    "Check dmesg output for “Focusrite ... Mixer Driver”:\n\n"
-
-    "dmesg | grep -A 5 -B 5 -i focusrite\n\n"
-
-    "For kernels before 6.7 you may need to create a file\n"
-    "/etc/modprobe.d/scarlett.conf\n"
-    "with an “options snd_usb_audio ...” line and reboot."
+    "Please check the prerequisites at:\n"
+    "https://github.com/geoffreybennett/alsa-scarlett-gui/"
  );
  gtk_widget_set_margin(label, 30);

--- a/src/iface-unknown.h
+++ b/src/iface-unknown.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/iface-update.c
+++ b/src/iface-update.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <gtk/gtk.h>
--- a/src/iface-update.h
+++ b/src/iface-update.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2024-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/img/alsa-scarlett-gui-logo.png
+++ b/src/img/alsa-scarlett-gui-logo.png
--- a/src/img/alsa-scarlett-gui.png
+++ b/src/img/alsa-scarlett-gui.png
--- a/src/img/audio-volume-high.svg
+++ b/src/img/audio-volume-high.svg
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="16px" viewBox="0 0 16 16" width="16px" xmlns="http://www.w3.org/2000/svg">
+    <path d="m 7 1.007812 c -0.296875 -0.003906 -0.578125 0.125 -0.769531 0.351563 l -3.230469 3.640625 h -1 c -1.09375 0 -2 0.84375 -2 2 v 2 c 0 1.089844 0.910156 2 2 2 h 1 l 3.230469 3.640625 c 0.210937 0.253906 0.492187 0.363281 0.769531 0.359375 z m 6.460938 0.960938 c -0.191407 -0.003906 -0.386719 0.054688 -0.558594 0.167969 c -0.457032 0.3125 -0.578125 0.933593 -0.269532 1.390625 c 1.824219 2.707031 1.824219 6.238281 0 8.945312 c -0.308593 0.457032 -0.1875 1.078125 0.269532 1.390625 c 0.457031 0.308594 1.078125 0.1875 1.390625 -0.269531 c 1.136719 -1.691406 1.707031 -3.640625 1.707031 -5.59375 s -0.570312 -3.902344 -1.707031 -5.59375 c -0.195313 -0.285156 -0.511719 -0.4375 -0.832031 -0.4375 z m -3.421876 2.019531 c -0.222656 -0.007812 -0.453124 0.058594 -0.644531 0.203125 c -0.261719 0.199219 -0.394531 0.5 -0.394531 0.804688 v 0.058594 c 0.011719 0.191406 0.074219 0.375 0.199219 0.535156 c 1.074219 1.429687 1.074219 3.390625 0 4.816406 c -0.125 0.164062 -0.1875 0.347656 -0.199219 0.535156 v 0.0625 c 0 0.304688 0.132812 0.605469 0.394531 0.804688 c 0.441407 0.332031 1.066407 0.242187 1.398438 -0.199219 c 0.804687 -1.066406 1.207031 -2.335937 1.207031 -3.609375 s -0.402344 -2.542969 -1.207031 -3.613281 c -0.183594 -0.246094 -0.464844 -0.382813 -0.753907 -0.398438 z m 0 0" fill="#ffffff"/>
+</svg>
--- a/src/img/audio-volume-low.svg
+++ b/src/img/audio-volume-low.svg
@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="16px" viewBox="0 0 16 16" width="16px" xmlns="http://www.w3.org/2000/svg">
+    <path d="m 7 1.007812 c -0.296875 -0.003906 -0.578125 0.125 -0.769531 0.351563 l -3.230469 3.640625 h -1 c -1.09375 0 -2 0.84375 -2 2 v 2 c 0 1.089844 0.910156 2 2 2 h 1 l 3.230469 3.640625 c 0.210937 0.253906 0.492187 0.363281 0.769531 0.359375 z m 2.957031 2.980469 c -0.199219 0.011719 -0.394531 0.074219 -0.5625 0.203125 c -0.441406 0.332032 -0.53125 0.960938 -0.195312 1.402344 c 1.074219 1.425781 1.074219 3.386719 0 4.8125 c -0.335938 0.441406 -0.246094 1.070312 0.195312 1.402344 c 0.441407 0.332031 1.066407 0.242187 1.398438 -0.195313 c 0.804687 -1.070312 1.207031 -2.339843 1.207031 -3.613281 s -0.402344 -2.542969 -1.207031 -3.613281 c -0.183594 -0.246094 -0.464844 -0.382813 -0.753907 -0.398438 c -0.027343 0 -0.054687 0 -0.085937 0 z m 0 0" fill="#ffffff"/>
+</svg>
--- a/src/img/audio-volume-medium.svg
+++ b/src/img/audio-volume-medium.svg
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="16px" viewBox="0 0 16 16" width="16px" xmlns="http://www.w3.org/2000/svg">
+    <g fill="#ffffff">
+        <path d="m 7 1.007812 c -0.296875 -0.003906 -0.578125 0.125 -0.769531 0.351563 l -3.230469 3.640625 h -1 c -1.09375 0 -2 0.84375 -2 2 v 2 c 0 1.089844 0.910156 2 2 2 h 1 l 3.230469 3.640625 c 0.210937 0.253906 0.492187 0.363281 0.769531 0.359375 z m 3.039062 2.980469 c -0.222656 -0.007812 -0.453124 0.058594 -0.644531 0.203125 c -0.261719 0.199219 -0.394531 0.5 -0.394531 0.804688 v 0.066406 c 0.011719 0.1875 0.078125 0.371094 0.199219 0.527344 c 1.074219 1.429687 1.074219 3.390625 0 4.816406 c -0.121094 0.160156 -0.1875 0.34375 -0.199219 0.53125 v 0.066406 c 0 0.304688 0.132812 0.605469 0.394531 0.804688 c 0.441407 0.332031 1.066407 0.242187 1.398438 -0.199219 c 0.804687 -1.066406 1.207031 -2.335937 1.207031 -3.609375 s -0.402344 -2.542969 -1.207031 -3.613281 c -0.183594 -0.246094 -0.464844 -0.382813 -0.753907 -0.398438 z m 0 0"/>
+        <path d="m 13.460938 1.96875 c -0.191407 -0.003906 -0.386719 0.054688 -0.558594 0.167969 c -0.457032 0.3125 -0.578125 0.933593 -0.269532 1.390625 c 1.824219 2.707031 1.824219 6.238281 0 8.945312 c -0.308593 0.457032 -0.1875 1.078125 0.269532 1.390625 c 0.457031 0.308594 1.078125 0.1875 1.390625 -0.269531 c 1.136719 -1.691406 1.707031 -3.640625 1.707031 -5.59375 s -0.570312 -3.902344 -1.707031 -5.59375 c -0.195313 -0.285156 -0.511719 -0.4375 -0.832031 -0.4375 z m 0 0" fill-opacity="0.34902"/>
+    </g>
+</svg>
--- a/src/img/audio-volume-muted.svg
+++ b/src/img/audio-volume-muted.svg
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg height="16px" viewBox="0 0 16 16" width="16px" xmlns="http://www.w3.org/2000/svg">
+    <g fill="#ffffff">
+        <path d="m 7 1.007812 c -0.296875 -0.003906 -0.578125 0.125 -0.769531 0.351563 l -3.230469 3.640625 h -1 c -1.09375 0 -2 0.84375 -2 2 v 2 c 0 1.089844 0.910156 2 2 2 h 1 l 3.230469 3.640625 c 0.210937 0.253906 0.492187 0.363281 0.769531 0.359375 z m 0 0"/>
+        <path d="m 10 5 c -0.265625 0 -0.519531 0.105469 -0.707031 0.292969 c -0.390625 0.390625 -0.390625 1.023437 0 1.414062 l 1.292969 1.292969 l -1.292969 1.292969 c -0.390625 0.390625 -0.390625 1.023437 0 1.414062 s 1.023437 0.390625 1.414062 0 l 1.292969 -1.292969 l 1.292969 1.292969 c 0.390625 0.390625 1.023437 0.390625 1.414062 0 s 0.390625 -1.023437 0 -1.414062 l -1.292969 -1.292969 l 1.292969 -1.292969 c 0.390625 -0.390625 0.390625 -1.023437 0 -1.414062 c -0.1875 -0.1875 -0.441406 -0.292969 -0.707031 -0.292969 s -0.519531 0.105469 -0.707031 0.292969 l -1.292969 1.292969 l -1.292969 -1.292969 c -0.1875 -0.1875 -0.441406 -0.292969 -0.707031 -0.292969 z m 0 0"/>
+    </g>
+</svg>
--- a/src/img/vu.b4.alsa-scarlett-gui.png
+++ b/src/img/vu.b4.alsa-scarlett-gui.png
--- a/src/img/vu.b4.alsa-scarlett-gui.svg
+++ b/src/img/vu.b4.alsa-scarlett-gui.svg
--- a/src/main.c
+++ b/src/main.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "alsa.h"
--- a/src/main.h
+++ b/src/main.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/menu.c
+++ b/src/menu.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "about.h"
--- a/src/menu.h
+++ b/src/menu.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/routing-drag-line.c
+++ b/src/routing-drag-line.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "routing-drag-line.h"
--- a/src/routing-drag-line.h
+++ b/src/routing-drag-line.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/routing-lines.c
+++ b/src/routing-lines.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "alsa.h"
@@ -237,7 +237,7 @@ static void get_snk_center(
  double             *y
 ) {
  get_widget_center(r_snk->socket_widget, parent, x, y);
-  if (IS_MIXER(r_snk->port_category))
+  if (IS_MIXER(r_snk->elem->port_category))
    (*y)++;
 }

@@ -261,6 +261,12 @@ void draw_routing_lines(
    struct routing_snk *r_snk = &g_array_index(
      card->routing_snks, struct routing_snk, i
    );
+    struct alsa_elem *elem = r_snk->elem;
+
+    // don't draw lines to read-only mixer sinks
+    if (elem->port_category == PC_MIX &&
+        card->has_fixed_mixer_inputs)
+      continue;

    // if dragging and a routing sink is being reconnected then draw
    // it with dots
@@ -271,7 +277,7 @@ void draw_routing_lines(
      cairo_set_dash(cr, NULL, 0, 0);

    // get the sink and skip if it's "Off"
-    int r_src_idx = alsa_get_elem_value(r_snk->elem);
+    int r_src_idx = alsa_get_elem_value(elem);
    if (!r_src_idx)
      continue;

@@ -300,7 +306,7 @@ void draw_routing_lines(
    draw_connection(
      cr,
      x1, y1, r_src->port_category,
-      x2, y2, r_snk->port_category,
+      x2, y2, elem->port_category,
      r, g, b, 2
    );
  }
@@ -362,7 +368,7 @@ void draw_drag_line(
    draw_connection(
      cr,
      x1, y1, card->src_drag->port_category,
-      x2, y2, card->snk_drag->port_category,
+      x2, y2, card->snk_drag->elem->port_category,
      1, 1, 1, 2
    );

--- a/src/routing-lines.h
+++ b/src/routing-lines.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/scarlett2-firmware.c
+++ b/src/scarlett2-firmware.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <glib.h>
@@ -72,7 +72,7 @@ struct scarlett2_firmware_header *scarlett2_read_firmware_header(
 ) {
  FILE *file = fopen(fn, "rb");
  if (!file) {
-    perror("fopen");
+    perror("fopen firmware header");
    fprintf(stderr, "Unable to open %s\n", fn);
    return NULL;
  }
@@ -91,7 +91,7 @@ struct scarlett2_firmware_header *scarlett2_read_firmware_header(
 struct scarlett2_firmware_file *scarlett2_read_firmware_file(const char *fn) {
  FILE *file = fopen(fn, "rb");
  if (!file) {
-    perror("fopen");
+    perror("fopen firmware file");
    fprintf(stderr, "Unable to open %s\n", fn);
    return NULL;
  }
@@ -265,7 +265,12 @@ static void enum_firmware_dir(const char *dir_name) {

 void scarlett2_enum_firmware(void) {
  init_best_firmware();
-  enum_firmware_dir(SCARLETT2_FIRMWARE_DIR);
+
+  const char *fw_dir = getenv("SCARLETT2_FIRMWARE_DIR");
+
+  if (!fw_dir)
+    fw_dir = SCARLETT2_FIRMWARE_DIR;
+  enum_firmware_dir(fw_dir);
 }

 uint32_t scarlett2_get_best_firmware_version(uint32_t pid) {
--- a/src/scarlett2-firmware.h
+++ b/src/scarlett2-firmware.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/stringhelper.c
+++ b/src/stringhelper.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <ctype.h>
--- a/src/stringhelper.h
+++ b/src/stringhelper.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/tooltips.c
+++ b/src/tooltips.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "tooltips.h"
--- a/src/tooltips.h
+++ b/src/tooltips.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/vu.b4.alsa-scarlett-gui.desktop.template
+++ b/src/vu.b4.alsa-scarlett-gui.desktop.template
@@ -1,6 +1,6 @@
 [Desktop Entry]
 Type=Application
-Name=ALSA Scarlett2 Control Panel
+Name=ALSA Scarlett Control Panel
 Icon=vu.b4.alsa-scarlett-gui
 Exec=PREFIX/bin/alsa-scarlett-gui
 Categories=GTK;AudioVideo;Audio;Mixer;
--- a/src/widget-boolean.c
+++ b/src/widget-boolean.c
@@ -1,30 +1,34 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

+#include "gtkhelper.h"
 #include "widget-boolean.h"

 struct boolean {
  struct alsa_elem *elem;
+  int               backwards;
  GtkWidget        *button;
+  guint             source;
  const char       *text[2];
+  GtkWidget        *icons[2];
 };

-static void button_clicked(GtkWidget *widget, struct alsa_elem *elem) {
+static void button_clicked(GtkWidget *widget, struct boolean *data) {
  int value = gtk_toggle_button_get_active(GTK_TOGGLE_BUTTON(widget));

-  alsa_set_elem_value(elem, value);
+  alsa_set_elem_value(data->elem, value ^ data->backwards);
 }

-static void toggle_button_set_text(GtkWidget *button, const char *text) {
+static void toggle_button_set_text(struct boolean *data, int value) {
+  const char *text = data->text[value];
+
  if (!text)
    return;

-  if (*text == '*') {
-    GtkWidget *icon = gtk_image_new_from_icon_name(text + 1);
-    gtk_button_set_child(GTK_BUTTON(button), icon);
-  } else {
-    gtk_button_set_label(GTK_BUTTON(button), text);
-  }
+  if (*text == '*')
+    gtk_button_set_child(GTK_BUTTON(data->button), data->icons[value]);
+  else
+    gtk_button_set_label(GTK_BUTTON(data->button), text);
 }

 static void toggle_button_updated(
@@ -36,10 +40,40 @@ static void toggle_button_updated(
  int is_writable = alsa_get_elem_writable(elem);
  gtk_widget_set_sensitive(data->button, is_writable);

-  int value = !!alsa_get_elem_value(elem);
+  int value = !!alsa_get_elem_value(elem) ^ data->backwards;
  gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(data->button), value);

-  toggle_button_set_text(data->button, data->text[value]);
+  toggle_button_set_text(data, value);
+}
+
+static gboolean update_toggle_button(struct boolean *data) {
+  toggle_button_updated(data->elem, data);
+
+  return G_SOURCE_CONTINUE;
+}
+
+static void on_destroy(struct boolean *data) {
+  if (data->source)
+    g_source_remove(data->source);
+
+  for (int i = 0; i < 2; i++)
+    if (data->icons[i])
+      g_object_unref(data->icons[i]);
+
+  g_free(data);
+}
+
+static void load_icons(struct boolean *data) {
+  for (int i = 0; i < 2; i++)
+    if (data->text[i] && *data->text[i] == '*') {
+      char *path = g_strdup_printf(
+        "/vu/b4/alsa-scarlett-gui/icons/%s.svg", data->text[i] + 1
+      );
+      data->icons[i] = gtk_image_new_from_resource(path);
+      gtk_widget_set_align(data->icons[i], GTK_ALIGN_CENTER, GTK_ALIGN_CENTER);
+      g_object_ref(data->icons[i]);
+      g_free(path);
+    }
 }

 GtkWidget *make_boolean_alsa_elem(
@@ -47,21 +81,26 @@ GtkWidget *make_boolean_alsa_elem(
  const char       *disabled_text,
  const char       *enabled_text
 ) {
-  struct boolean *data = g_malloc(sizeof(struct boolean));
+  struct boolean *data = g_malloc0(sizeof(struct boolean));
  data->elem = elem;
  data->button = gtk_toggle_button_new();

+  if (strncmp(elem->name, "Master", 6) == 0 &&
+      strstr(elem->name, "Playback Switch"))
+    data->backwards = 1;
+
  g_signal_connect(
-    data->button, "clicked", G_CALLBACK(button_clicked), elem
+    data->button, "clicked", G_CALLBACK(button_clicked), data
  );
  alsa_elem_add_callback(elem, toggle_button_updated, data);
  data->text[0] = disabled_text;
  data->text[1] = enabled_text;
+  load_icons(data);

  // find the maximum width and height of both possible labels
  int max_width = 0, max_height = 0;
  for (int i = 0; i < 2; i++) {
-    toggle_button_set_text(data->button, data->text[i]);
+    toggle_button_set_text(data, i);

    GtkRequisition *size = gtk_requisition_new();
    gtk_widget_get_preferred_size(data->button, size, NULL);
@@ -78,5 +117,12 @@ GtkWidget *make_boolean_alsa_elem(

  toggle_button_updated(elem, data);

+  // periodically update volatile controls
+  if (alsa_get_elem_volatile(elem))
+    data->source =
+      g_timeout_add_seconds(1, (GSourceFunc)update_toggle_button, data);
+
+  g_object_weak_ref(G_OBJECT(data->button), (GWeakNotify)on_destroy, data);
+
  return data->button;
 }
--- a/src/widget-boolean.h
+++ b/src/widget-boolean.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/widget-drop-down.c
+++ b/src/widget-drop-down.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include <ctype.h>
--- a/src/widget-drop-down.h
+++ b/src/widget-drop-down.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/widget-dual.c
+++ b/src/widget-dual.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "widget-dual.h"
--- a/src/widget-dual.h
+++ b/src/widget-dual.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/widget-gain.c
+++ b/src/widget-gain.c
@@ -1,9 +1,10 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "gtkdial.h"
 #include "stringhelper.h"
 #include "widget-gain.h"
+#include "db.h"

 struct gain {
  struct alsa_elem *elem;
@@ -56,24 +57,39 @@ static void gain_updated(

  char s[20];
  char *p = s;
-  float value = (float)alsa_value * data->scale + elem->min_dB;
+  float value;
+  int min_db = round(elem->min_cdB / 100.0);
+  int max_db = round(elem->max_cdB / 100.0);

-  if (value > elem->max_dB)
-    value = elem->max_dB;
-  else if (value < elem->min_dB)
-    value = elem->min_dB;
+  if (elem->dB_type == SND_CTL_TLVT_DB_LINEAR) {
+    value = linear_value_to_db(
+      alsa_value,
+      elem->min_val,
+      elem->max_val,
+      min_db,
+      max_db
+    );
+  } else {
+    value = ((float)(alsa_value - elem->min_val)) * data->scale + (elem->min_cdB / 100.0);
+    if (value > max_db)
+      value = max_db;
+    else if (value < min_db)
+      value = min_db;
+  }

-  if (data->zero_is_off && alsa_value == 0) {
+  if (data->zero_is_off && value == min_db) {
    p += sprintf(p, "−∞");
  } else {
+    if (data->scale <= 0.5)
+      value = round(value * 10) / 10;
    if (value < 0)
      p += sprintf(p, "−");
    else if (value > 0)
      p += sprintf(p, "+");
    if (data->scale <= 0.5)
-      p += sprintf(p, "%.1f", fabs(value));
+      p += snprintf(p, 10, "%.1f", fabs(value));
    else
-      p += sprintf(p, "%.0f", fabs(value));
+      p += snprintf(p, 10, "%.0f", fabs(value));
  }
  if (data->scale > 0.5)
    p += sprintf(p, "dB");
@@ -159,20 +175,42 @@ GtkWidget *make_gain_alsa_elem(
  gtk_widget_set_valign(data->vbox, GTK_ALIGN_START);
  gtk_widget_set_vexpand(data->vbox, TRUE);

-  data->scale = (float)(elem->max_dB - elem->min_dB) /
-                       (elem->max_val - elem->min_val);
+  gboolean is_linear = elem->dB_type == SND_CTL_TLVT_DB_LINEAR;
+  double step;

+  if (is_linear) {
+    data->scale = 0.5;
+    step = 0.5;
+  } else {
+    data->scale = (float)(elem->max_cdB - elem->min_cdB) / 100.0 /
+                         (elem->max_val - elem->min_val);
+    step = 1;
+  }
  data->dial = gtk_dial_new_with_range(
    elem->min_val,
    elem->max_val,
-    1,
+    step,
    3 / data->scale
  );

  // calculate 0dB value
-  int zero_db_value = (int)((0 - elem->min_dB) / data->scale + elem->min_val);
+  int zero_db_value;
+
+  if (is_linear) {
+    zero_db_value = cdb_to_linear_value(
+      0,
+      elem->min_val,
+      elem->max_val,
+      elem->min_cdB,
+      elem->max_cdB
+    );
+  } else {
+    zero_db_value =
+      (int)((0 - elem->min_cdB) / 100.0 / data->scale + elem->min_val);
+  }

  gtk_dial_set_zero_db(GTK_DIAL(data->dial), zero_db_value);
+  gtk_dial_set_is_linear(GTK_DIAL(data->dial), is_linear);

  // convert from widget_taper to gtk_dial_taper
  int gtk_dial_taper;
--- a/src/widget-gain.h
+++ b/src/widget-gain.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2022-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2022-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/src/widget-input-select.c
+++ b/src/widget-input-select.c
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #include "stringhelper.h"
--- a/src/widget-input-select.h
+++ b/src/widget-input-select.h
@@ -1,4 +1,4 @@
-// SPDX-FileCopyrightText: 2023-2024 Geoffrey D. Bennett <g@b4.vu>
+// SPDX-FileCopyrightText: 2023-2025 Geoffrey D. Bennett <g@b4.vu>
 // SPDX-License-Identifier: GPL-3.0-or-later

 #pragma once
--- a/Show More
+++ b/Show More