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
From what I have been reading the current vintage of asynchronous USB DACs have closed the gap with other interfaces. However, I will have a good old transport on standby to hear for myself.
All blanket statements are inherently incorrect. LOL....how's that for a blanket statement?

The interface implementation is paramount, whatever the interface. Jitter reduction is what most of hear as differences between transports/interfaces. There is hope though....all digital is improving as designers understand more and more as well as the trickle down of technology advances to more affordable levels.
dCS streams PCM and DSD via USB and from what I've heard, the sound is up there with the best of them. There is a lot of misleading marketing going on with digital.
Case in point: "the length of a USB cable can't exceed 3 meters". I've read that a lot and yet I have a 5 meter length of Wireworld USB cable that begs to differ.
Its what at the receiving end that matters.