Importance of computer for DAC shootout


I am using a perfectwave DAC + bridge + modwright 36.5 LS/PS preamp to stream flacs over my network. Very happy with the sound, but intrigued by the idea of getting better SQ for less $$$ I will soon be auditioning an Antelope Zodiac Gold + Volticus over USB, directly into my poweramp. Being able to take out the modwright alone would pay for the new DAC. My only concern is the Computer I will be using for this shootout. I have a Dell laptop and an Asus media PC, both with USB 1.0.

If I opt for the Zodiac I will go all out on computer source (may be mach2music), but I don't want to invest before knowing if I even want to go down the USB path.

In you estimation, is there any chance of the computer used in my shootout distorting the outcome? Would I be better off using my Marantz ud9004 S/PDIF source for the Zodiac, and then get a better computer if the Zodiac wins the contest?

Or are the difference between computer sources small and will I be able to conclude which is the better DAC using a mediocre PC as the source for the Zodiac. Any advise on how to set up the hardware for the shootout is welcome.
edorr
"Call me an audio snob but I am deeply sceptical of $300 devices being able to perform at the level of mac based music server architectures, used by computer audiophiles the world over. "

Well, one is entitled to be skeptical but I suspect that one would be mistaken.

What is it exactly that makes a mac based music server architecture so special again for audiophiles?

Actually the DAC in the latest Squeezebox Touch specifically is rumored to be pretty good but I have not even tried it in that I had my DAC nailed down prior to going with the Squeeze devices.

A Mac based music server is fine. Squeezeserver runs on Macs, PCs, and other OSs, so you can use Squeeze players and your DAC of choice with a Mac music server.

But if the "mac based music server architecture" is so good, why use a third party DAC at all? Just use the one in the Mac and be done with it.
We're going off on a tangent. I have a phenomenally sounding PS AUdio Perfectwave DAC, streaming over the network. I am just intruiged by an reportedy very good altenative DAC with analog volume control. I want to make sure the computer I use to feed the DAC over USB is not the "weakest link" potentially distorting the outcome of a shootout. To this end, I bought a used Mac for a price I can easily resell it for. I think I'm all set.
I suppose it depends on how well the mac works out then. I'm hoping it does.

But to answer your question I am also saying that the choice of device feeding the DAC and the intereface used can make a difference in the sound. If the Mac or other computers via USB does not pan out, then I would recommend considering the Squeezebox Touch feeding your DAC as a very robust alternative in your case.
OK - thanks. Don't get me wrong - I appreciate all the advise I am getting here. I placed my bet on the Mac Mini. Next let's see who wins the shootout. If its a close call I may try some other USB source, but most likely I would get an external powersupply for the Mac first to see if that would swing the vote. I guess I should also get at least a half decent aftermarket USB cable. Damn, this never ends....
Why USB? A good soundcard w/spdif out will blow away the usb (unless you spend mega bucks (and still...). Don't limit yourself to usb, it's the poorest interface. Try different sources and you can easilly hear the problems with usb.