I'm mostly interested in analog inputs in the DAC's so I can have a passive preamp as an alternative to my tube preamp without spending more money. While I'm pretty happy with my Odyssey Candela tube pre, it doesn't sound quite as good for some genres such as classical. I actually found an explanation for how to add a digital out to a cd player: http://www.turboegt.com/Audio/Car%20Audio/Digital%20Outs/digital_outpu-f.htm although I'm not sure how reliable the instructions are because I have little technical knowledge..
As far as a music server goes, I only have one system so I just figured I'd connect my desktop to the DAC via USB. Is there a reason why I'd want a dedicated music server as opposed to a desktop?