[linux-audio-user] tell ALSA to use secondary card (on USB) instead of primary

I've a nice headphone amp that's connected via USB (*) and it's
essentially a second sound card in the system.

With XMMS it's pretty easy to tell it to use the second "card": I go to
Output Plugin / ALSA / Device settings / Audio device and I choose
hw:2,0
Then I go to Device settings / Mixer card and choose USB Audio CODEC.

But I'd like to use this "card" also for the Flash plugin in Firefox
(wrapped in aoss), and for Xine. Ideally, I'd like all ALSA applications
under this user account to use the USB amp instead of the primary card.

I'm pretty sure there has to be a way to configure ALSA to direct all
apps to the second card by default, but I can't seem to figure out how.
Any suggestion is appreciated.

(*) - It's actually Headroom's Total BitHead amp, bought together with a
Sennheiser HD280 Pro in the "Back to School" package:

http://www.headphone.com/products/packaged-systems/back-to-school-sealed.php

The amp is based on the Burr-Brown PCM2902E chip which is compatible
with a variety of OSes, including Linux/ALSA.
The Senn cans are actually amazingly good, at least for the definition
of "good" applicable to sealed phones; they sound pretty much like
midrange / high end-ish open air phones, with the added benefit of the
isolation provided by the closed back.

-- 
Florin Andrei
http://florin.myip.org/