Mac mini vs Macbook PC audio sound quality

Does it make a difference in sound quality from Mac mini/desktop
or Macbook/Powerbook to usb to dac?
I doubt it. The source files (MP3, WAF, AIFF,etc.) and the DAC will make all the difference.
I think the Mini has the advantage because of its sheer physical quietness,
just be careful that on MacBook, iTune's EQ is turned on by default, you will have to turn it off manual the first time. At least this is what I've experienced.
thanks abe av that was very insightful