Does the Quality of the USB cable matter?

Ed, what kind of interface do you have between the MacMini and your DAC (USB, ethernet, S/PDIF, etc.)? And how much distance is there between the firewire cable and the DAC (and its cabling), as well as between the firewire cable and the rest of the audio system?

My suspicion is that your findings may have little if any applicability to Ozzy's situation. In his case the external drive is 50 feet away from anything that may directly impact sound quality, since an ethernet interface is used to cover that 50 foot distance, and jitter that may be induced by digital noise is essentially irrelevant for an ethernet interface, due to the packetized and buffered nature of data transmission and reception over that kind of interface.

Regards,
-- Al

Would these comments be the same if we were discussing Firewire?

Yes, cables make a difference. By a little.

Thanks everyone fo the help. I have the DH Labs USB cable and will try it out this weekend.

I tried the DH Labs USB cable for a little while Saturday, and I thought I was hearing more body to the music than I had when using my cheapo USB cable.
So to make the comparison fair I've put the Dh Labs cable USB on my cable cooker for a few days and I will insert it back into my system then.