Hi Uwe, I've got some interesting news. I now used Fedora 42 for 12 days without any issues. So today I started booting Ubuntu 25.04 from USB, and after just over an hour of usage the issue appeared. So whatever the cause is, it seems to be limited to Debian and its derivatives. while Fedora doesn't seem to be affected at all. So whatever the cause is, it's not due to anything I did, it's there by default.
I also tried your recommendations: aplay -l did in fact still show the expansion card, and so did lsusb. systemctl soft-reboot did not fix anything, though I'll check out both again the next time this issue happens on my Debian system. Best regards Richard
