Newbe PC audio

Probably the simplest way would be to buy an Airport Express base station, connect to it from your PC (it works for PC's or Macs as a wireless access point or can be installed on your wired ethernet network.) Then connect the Airport Express and your DAC via their digital optical connectors. The analog output of the DAC connects to one of the inputs on your preamp.

A lot of people use the Squeezebox products but I have no experience with them.

Airport Express would work, but the sound wouldn't be up to your standards -I think- based on the rest of your system. And you don't own own Mac.

Really, your best bet is to go wired somehow. There are lots of possibilities! Here are links to informative manufacturer sites with information pages on computer audio to get you up to speed on available options.

If you like tubes, I wholeheartedly recommend Wavelengh Audio.

Wavelength Audio

Empirical Audio

Also, here is a really good site dedicated to computer audio run by a guy in Minneapolis, MN:

Computer Audiophile

Lots of possibilities. The best, but expensive option would be the Empirical Audio stuff. Alternatively you can go with a DAC that already looks after the jitter issue to a decent degree such as the Benchmark. Unfortunately the sterile DAC-1 probably wouldn't be to your liking (it's not to mine). I have a Paradisea+ tube DAC connected to my Vista desktop via a FOCUSRITE SAFFIRE Le.

http://www.focusrite.com/products/saffire/saffire_le/

The DAC1 USB will work more than fine. It can be a bit clinical depending on setup and what it's paired with, but handles jitter very well. Like most resolving gear, it reacts to power cords/ICs and reveals weaknesses elsewhere.