Is this a reasonable Audiophile Mac-based Server?

thanks pwfletcher,
i really hope its not a prob with the dac. i've talked to bel canto directly and they think the issue is with the mac.i tried a little experiment which was using my dvd player as a transport feeding the dac. seemed to work fine! connection made with digital coax. next i tried using the mac as the transport (no rip, just playback). no luck, same results- does the dac read usb and coax differently?
I just got off the apple site and apparently it sounds like itunes 7.6 might be the issue. many people complaining about similar problems. (skipping, drop outs) i tried trashing the itunes app., then reinstalling it. - no luck -
man, it would really be nice to get to the bottom of this.
oh yea, apple care hasn't a clue! ?????????

Go here to get an older version and try that

http://www.oldapps.com/download_iTunes_mac.php

I still don't believe that toslink is inferior. If all the bits get there and the interface is designed properly how could it be inferior. It has to be a problem with the DAC or jitter from the source if it sounds different. Perhaps the DAC designer figures no self respecting audiophile will use toslink so they don't put any effort in to it. These comparisons I see prove nothing about toslink, just about toslink on the particular DACs and sources used in the shoot out.

That said if the DAC you choose does have an inferior optical input then you should use another input.

As Pwfletcher says: Plug the USB cable directly into the Mini and not a hub (if you are going to use a hub make sure it a powered one with its own wall wart). Because a) it will have direct access to the USB and because b) it will have sufficient power - remember USB carries 5v.

Yes a DAC will probably see USB differently then coax. Coax is coming in SPDIF, USB is coming in USB and then has to be converted to SPDIF.

Based on everyone's comments it is starting to sound as though the Bel Canto is very sensitive to signal level.

Although it is a very nice piece of equipment, I find it hard to believe that the USB DAC sounds better than a Transporter set up correctly using the optimal hardware and software settings for the Transporter and slim server. There are so many factors that make a BIG difference. For example, the TP balanced output is dramatically different than the SE output. MP3 transcoding is dramatically different than other options, etc. You simply cannot do a simple A/B test. The basic beauty of the TP is that it contains a great DAC and you eliminate more jitter inducing steps (USB, Toslink, etc.).

I have a SILVERSTONE ENSEMBLE EB01 USB DAC connected to my MacPro, i then stream my music via AirPort Express to my Cambridge Audio Azur 540v2 via Toslink.

My Question is: Does having my USB DAC connected to my computer before I stream the music to my receiver a good thing? I wasnt sure if having the DAC connected to my computer before streaming the music defeated the purpose of having a DAC. I have noticed that everyone else has their DAC connected to to AirPort Express.

Let me know if this doesnt make sense? Thanks for any insight.