Dynobot,
....
But unless I missed it you don't say which DAC etc you were listening to, or perhps this choice was independent of the rest of your audio chain..
Although Im a dedicated Linux user I still have not built a separate "audio computer", yet I lean towards an Atom powered device or using an embedded sytesm like one of the ALIX m/boards combined with VoaygeMPD linux. Talking of which have you ever seen this website?
http://kubotayo.web.fc2.com/voyagempd.html
It includes some patches for MPD itself to make further use of real time capabilities. I've made no use of these myslef yet so can't say if they are effective. But they are accompanied by a detailed description.
One last question, I wonder if you had ever tried the switch from ALSA to OSS4? Sadly, my DAC's USB connection does not function although recognised in OSS4 , but my Envy24HT card works OK.