The simplest and least expensive way to get superb audio quality as well as great user interface - use your own computer, but add external boxes to get WiFi or networked interface and then reclock to get excellent sound quality.
First, decide on the interface you like. Most like iTunes best. Apple is the leader in this industry afterall. The problem is there is only S/PDIF wired or AirPort Express WiFi. Both have poor digital audio quality - lots of jitter. To solve this, add a Pace-Car reclocker.
Then you need a really good DAC. The lowest jitter solutions have I2S interface, such as the Northstar 192 DAC.
If you decide to go the USB route, then the bargain of the century is the DAC-1 USB. Sound quality is good, and can be improved with some mods. USB has the wire of course, but will allow you to use virtually any player software. I woudl avoid iTunes unless you use a MAC.
Forget about sound-cards and silent PC's. This is old technology. Now we have Sonos, Squeezebox, AirPort Express, Off-Ramp and DAC-1 USB.
Steve N.
Empirical Audio