An ancient and defective analog mixer is repurposed as a control device for all kinds of settings of a linux sound system (alsa/pulseaudio/pipewire).
A pi pico running micropython code is used to collect slider, potentiometer and switch settings. It then sends the data to the host via USB to another piece of python code, which then changes the sound server settings accordingly.
Two rotary encoders are used to set master volume and active sink volume gain.
The slider positions and potentiometer values are polled from three 8-channel ADCs. One of the equaliser blocks sets the hardware equaliser and equalitser gain of a creative Audigy sound card. The other is used to control output channel volumes (Front/Rear/Center/LFE).
A rotary switch with 6 positions controls the active sink profile (like Front/Rear swap for music or high Center gain for spoken content).