When plugged-in, the soundcard was given a different idProduct than expected (1011 instead of 1010).
- Open file /lib/udev/rules.d/90-pulseaudio.rules
- Find line with text
usb 1-2: New USB device found, idVendor=17cc, idProduct=1011
- Change value 1011 to 1010
- Restart pulseaudio server
pulseaudio -k
Add default stereo scheme
- Open file /usr/share/pulseaudio/alsa-mixer/profile-sets/default.conf
- Add new mapping
[Mapping analog-surround-20]
description = Analog Stereo
device-strings = surround21:%f
channel-map = front-left,front-right
paths-output = analog-output analog-output-lineout analog-output-speaker
priority = 10
direction = output
Set default input source:
pacmd set-default-source alsa_input.pci-0000_00_1f.3-platform-skl_hda_dsp_generic.HiFi__hw_sofhdadsp_6__source