My Dell 690 at work has lots of audio devices and I couldn't figure out how to get all sound to go to the Audigy2. I found a tip about changing /etc/modprobe.d/alsa-base to include the line #options snd_emu10k1 index=0 and that worked but... ALSA would get hung up occasionally when a window opened. Pete suggested that I turn off ESD and I tried that, but then the Audigy2 was not detected. I found that either enabling ESD or deleting that line above would restore its function. I deleted that line and found this tip for how to fix it. The simple answer appears to be:

sudo asoundconf set-default-card Audigy2