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How to change the default sound card in Ubuntu

If you have installed a second sound card into your computer you may find your onboard sound card is still the default, even if you have disabled the onboard in the bios.

Identify the problem

cat /proc/asound/cards
0 [SB]: HDA-Intel - HDA ATI SB
HDA ATI SB at 0xfebf8000 irq 18
1 [CA0106]: CA0106 - CA0106
Audigy SE [SB0570] at 0x8c00 irq 20

As you can see the onboard ATI/AMD sound card is card 0 and the Audigy SE card is card 1

Identify the modules

cat /proc/asound/modules
0 snd_hda_intel
1 snd-ca0106

So snd_hda_intel is the onboard, snd-ca0106 is the Audigy

Method 1, Disable onboard

echo 'blacklist snd_hda_intel' | sudo tee -a /etc/modprobe.d/blacklist

This will prevent the snd_hda_intel driver from loading on boot

Method 2, Swap the default sound card

echo -e 'options snd-ca0106 index=0/noptions snd_hda_intel index=1' | sudo tee -a /etc/modprobe.d/alsa-base

Reboot and test

check cat /proc/asound/cards to see if Audigy SE is now card 0 and test the sound