I'm really looking at the motherboard digital output>5.1 decoder/DSP/amplifier threads as this should be the way to go - even if the preferred item isn't jumping off the page just yet.
In the meantime, I have tried an External Soundblaster (extigy 2ns I think) - this had a huge driver! - it was also powered by 5v, and given the current restrictions of many car-based DC-DCs created some issues. I was also concerned by the number of USB devices contesting the same bus.
OK - so this looks worthy of a mention: A new firewire device from Behringer.
http://www.behringer.com/FCA202/index.cfm?lang=ENG
Firewire
Metal case
Small device drivers (CPU overhead not known)
12v 200ma power (compare that to the external soundblasters!)
Cheap - about £60 in the UK.
Only 2-channel though.
Its not out just yet(end of Nov), but it looks to provide a good external option.
Linear Mode
