the best, cost-no-object, music streamer?

The USB input on the McIntosh is asynchronous, so you are effectively using the clock on the c48. When you put a very good USB converter between the c48 and the Mac, the clock in the USB converter will provide the masterclock to the c48 instead (assuming the S/PDIF inputs are synchronous). It is conceivable this will sound better, but not a foregone conclusion. Only way to find out is to try. You could get one of Steve's Offramp 5 converters. I believe he has 30 day return policy, so if you hear no impovement you send it back.

Nd4 - I am planning on designing a version of my USB module using XMOS parts in the near future, that is if I can get some cooperation from them....

Steve N.
Empirical Audio

"Is there something wrong with my setup? should i buy a master clock?

has anybody tried a master clock, how much "less jitter" does the unit do the whole music experience?"

Most DACs can be improved dramatically by adding an external USB converter with a low-jitter clock. This is THE MOST IMPORTANT part of the digital system, not the DAC.

Lower jitter will get you much better imaging, dynamics and bass tightness. Wider and deeper soundstage. The more you spend for the USB converter and associated USB and S/PDIF or I2S cables, the better the result.

Steve N.
Empirical Audio

Steve N.,

When you said USB converter, did you mean USB cable from A type USB (MacMini) to B ?

"From reading the posts it seems music streamer needs to be a dedicated unit like sooloos, aurender, linn etc. I've only seen and hear the sooloos. seems the presentation (demo) wasnt setup well in front of me. or probly the music was using a file that is compressed and lossy."

Not necessarily, I think there are a number of "open" streaming systems that work with multiple brand. For example, tHe Simaudio 180 streamer works with any dac and a PC, Apple or NAS with a UPnP library management system for music storage. I think PS Audio and Linn are also open, or at least partially open streaming systems.