I would check out the discussions at
http://www.computeraudiophile.com/content/Computer-Audiophile-Pocket-Server-CAPS-v20
computeraudiophile.com
They do not recommend connecting outboard DACs to standard computer hardware. There are numerous problems effecting the quality of the digital data (the USB being a major one). After reading some stuff there, I have put off consideration of a commercial PC or Mac for a music server. The OS also plays a major role with some file formats (like Win 7).
http://www.computeraudiophile.com/content/Computer-Audiophile-Pocket-Server-CAPS-v20
computeraudiophile.com
They do not recommend connecting outboard DACs to standard computer hardware. There are numerous problems effecting the quality of the digital data (the USB being a major one). After reading some stuff there, I have put off consideration of a commercial PC or Mac for a music server. The OS also plays a major role with some file formats (like Win 7).