http://www.audioscience.com/, but you'll need your own (AD|DA)Cs
this might be incorrect. the descriptions mention 'balanced analog inputs and
outputs' , but i dont see any kind of breakout box or rack mount unit..
also check out the PCI options from Echo. they have nice drivers, dmix isnt supported
AFAIK but you dont get a multi-channel setup to do software mixing anyways..