Using surround sound outputs separately?

[Ian Malone]

I've had a couple of Googles at this, but it's hard to pick the right
keywords and I've not hit anything.

Has anyone got a surround sound card (5.1 or 7.1) to separately output
stereo on two pairs of channels or able to suggest how?  What I've got
is a 7.1 card with 4 stereo out jacks, which mostly has my monitor
speakers plugged into the main output, and a separate stereo speaker
set with amplifier (which is usually turned off).  I'd like to be able
to have the amplifier plugged into one of the other channels and be
able to swap the output between the two from the desktop.  Is setting
the system up as 4.0 and using forward/backward fade the best way to
accomplish this, or are things which can output in surround (like
DVDs) going to be confused by the arrangement?

Thanks for your time.
-- 
imalone