How can I control which sound card Ubuntu uses for playback?

Question

I am dual-booting Ubuntu 9.04 and Windows XP but am new to Ubuntu. In Windows, I use an M-Audio Audiophile 2496 sound card for recording (because it has RCA input jacks for my mixer), but I don't use it for playback (because my speakers use a 1/8 inch jack); instead, I use the motherboard's built-in sound card.

I tried to recreate this arrangement in Ubuntu, but despite selecting the built-in card for all playback under System > Preferences > Sound, I still have inconsistent results. Rhythmbox plays back through the integrated card, but Flash content in the browser and games in the OS send their audio to the Audiophile card.

I have seen recommendations to use a program called "Jack" to control this, but I installed it and found it baffling.

How can I control which card is used for playback, other than disabling one card (as I discovered how to do and explain below)? Also, is there a GUI for disabling hardware, or is it necessary to edit a configuration file?

Answer 1

Since I don't really need the PCI sound card to work when I'm booting Ubuntu, I eliminated the confusion by disabling it. Here's how:

1) I opened Terminal and typed less /proc/asound/modules to get a list of the audio drivers being used
2) There were two listed: snd_hda_intel, which I recognized as the built-in sound card, and snd_ice1712, which I guessed was the Audiophile 2496
3) From terminal, I typed sudo gedit /etc/modprobe.d/blacklist.conf to edit the list of drivers that are "blacklisted," meaning they are not loaded at startup. I added these lines to the bottom of the file:

#Disable M-Audio Audiophile 2496
blacklist snd_ice1712

4) I rebooted. Now the Audiophile card was disabled and all sound came through the built-in card. Success!

Note: I found this solution mainly here, so thanks to natewiebe13.