Is this a reasonable Audiophile Mac-based Server?

Looks good to me. This is nearly identical to my setup. However I use software on a Mac Mini to control multiple CD players as the source rather than iTunes/hard drive source...of course my setup is 7 years old and, at the design time, ripping a thousand CD's to lossless files was impractical (costly)...ripping to a hard drive still remains a daunting task for me one day when I eventually go to a raid server based source (which I certainly will).

Being able to sit in the listening chair and select and cue music and surf the web for information about the artist and/or musical piece that I am listening too is simply wonderful ( I feel like Austin Powers - yeah Baby!) - certainly better compared to fiddling with CD Jewel cases and feeding a CD tray and punching buttons to select the appropriate track to play all of which just gets in the way of the music)...

FWIW - I think your solution is well thought out.

Synthfreek - good point - I use that setup but no DAC - my mac mini directly controls ALL sources (including CD player preamp and source selection via an USB to serial link to an infra red controller box)

I use a wireless keyboard with roller ball mouse. I use my HDTV as a screen. (Mac Mini can output 720P with some slight mods to the software that controls the video card)

But feel free to ignore this as I did quite a bit of programming for my setup so that I can control everything (even switch on and off any components using my Mac from my wireless keyboard at the listening position). My setup is for the more technically inclined.

Amazing all the conjecture against Wireless 802 system and in preference for USB.....IMHO both should sound indistinguishable provided you buy modestly good gear...after all none of this is rocket science...do we really suspect manufacurers are all inept and incapable of building something that works.

What happens at the clock in the DAC itself is anyone's guess in a specific setup with your house mains power and whatever other applicances you have connected - but rest assured that most manufacturers are building perfectly good gear. There is no reason to be assuming the worst from teh outset until you find a problem. There is no cause for such fears from the outset.

As for me, I would build it and then cross check it against a CD player direct into the amp (using exactly the same test tracks as on iTunes) - that is what I have always done in the past (switching back and forth with the remote endlessly until I am satisfied I have no idea which one is which). If you can't hear any difference after this kind of extensive auditioning then it is good enough to stop worrying (just make sure to precisely level match volumes as even a very slight increase in loudness sounds better)

I would test your DAC with another software and PC than iTunes and your mac mini. There are many programs that play music....surely you can find something and just test to see if you get drop outs...in which case it would lead one to suspect the DAC.

Is there anything else that might be hogging the USB bus...do you have a dongle and wireless mouse or something plugged into USB (printer/scanner)that might cause latency in the USB port?