It was a matter of selecting the right combination of device and profile out of the many possible combinations. It was complicated by the fact that changing a profile could change the device selection. Also, the Test Speakers function worked OK for a lot of selections - I needed to be playing an actual video to find the one combination that actually works.
I downloaded the latest Debian 12 live ISO (MATE, because that's what have installed), booted it and audio was fine without any screwing around. The Sound Preferences displayed a significantly different and much smaller set of selections and there were multiple selections that worked. Ideally the upgrade process should manage this correctly, but, if that's not possible then there needs to be something about this in the upgrade instructions. Since the ISO comes up with something different from the upgrade, I have to assume, even though the audio is now working, that the audio setup is incorrect. But, I don't know how to clean it up. -- Christopher Witkowski
