Plugging in an USB sound card to a linux machine can be quite frustrating because it does not become the default device automatically. Today I read about such an option in alsa that I didn’t know about before.
All you have to do is to open the /etc/modprobe.d/alsa-base.conf as root and toggle out a line.
Looks for this section…
# Keep snd-usb-audio from beeing loaded as first soundcard options snd-usb-audio index=-2
…and make it look like this:
# Keep snd-usb-audio from beeing loaded as first soundcard # options snd-usb-audio index=-2
After a reboot your USB sound card is the default card for alsa when plugged in.