I attempted to get the system to default to my USB audio device. Unfortunately, I used guidance that predated Buster that apparently is no longer valid. Specifically, I followed these steps:
sudo nano /usr/share/alsa/alsa.conf
Scrolled and found the following two lines:
defaults.ctl.card 0
defaults.pcm.card 0
Changed the 0 to a 2 to match the card number of my USB device :
After doing this, the speaker icon/volume control on the GUI/desktop has a red X on it. In addition, the aplay - l and alsamixer commands no longer function and throw off error messages: unexpected char, invalid argument.
I undid the changes to alsa.conf but I'm still getting the same errors and no audio. Perhaps I accidentally did something else to the file.
So what is the best way to return things to normal? Does the problem lie within the alsa.conf file only and if so is there an easy way to replace just it? Or, does the damage extend to other components of alsa? I'm looking for the simplest fix possible that hopefully would not involve reflashing the SD card. Thanks!