Okay, i had to try it today...
Unfortunatley, it was set to "PC/Mac" already. I have factory reset the card and tried again.
Have you enabled the sbx profile, or do you use direcr sound mode?
After some more testing, I think this is indeed the case. The problem is that the device has two input channels ("line-in", " external mic"). In alsamixer i can select both as "PCM capture source" (from here)
However, the input tab of pavucontrol, i can only select "line in". I switched through all available profiles for the card. But the dropdown only always show "line-in"
I could do that, the question is what is the correct config file?
I think the .state files are more like snapshots wich are applied to the config when i restore it.
I still habe this in my project todo list: https://github.com/MiczFlor/RPi-Jukebox-RFID