want to

You need something to provide the signal (the Mac) and another device sitting with your big rig that will take this signal and do the decoding etc. needed for playback by the analog amps.

You might want to look at the WD TV Live product, seems to do a lot for the money:

http://wdc.com/en/products/products.aspx?id=320

-RW-

I use a Squeezbox Duet to do just this very thing. It hooks up through my WiFi network, so you don't even need a direct computer connection. It works fantastic. I do feed the digital output to my EE MiniMax DAC, but it does have a built-in DAC with analog outputs, so you can use it without an outboard DAC. A Squeezbox Touch will also work.

Cheapest Apple thing is an AirPort Express. Uses itunes, but requires either a DAC and amps or SS receiver. Better options are Logitech Squeezebox Touch or Sonos. The DAC in the Touch is the best sounding. You will need an amplifier and speakers with Touch.

With Sonos, you can get their Play:3 or Play:5 These have everything you need including amps and speakers. These are the simplest one-box solutions.

Steve N.
Empirical Audio

Squeezebox TOUCH

Another option, although I have no experience with it, would be the NuForce Air DAC system. I believe the Touch will give you the highest quality of all the options presented so far. I just installed one last month, it works great.