Media volume-control keys don't work with external USB audio device

Hello,

The external USB audio device is jailed inside the USB qube and attached to an app qube audio.

The audio qube has installed qubes-usb-proxy, pavucontrol and pulseaudio-qubes.

Sound works so far inside audio, but problem is: keyboard media don’t have an effect on the USB audio device (USB keyboard also being jailed). They do work with speakers plugged into usual audio jack inside audio.

My manual workarounds are:

  • adjust pavucontrol volume control slider with mouse
  • Some scripting like pactl set-sink-volume 1 +10%

Related:

, but these links are rather orthogonal to issue, as media keys and USB audio in general work.

How might I adjust USB audio sound with keyboard media keys? Or is some scripting necessary?