I have found after a few hours use that I was getting audio break ups. Turning passthru off then back on cleared them.

This lead to experimentation and I have found using the analogue inputs gives me a much better sound, the DAC in the squeezebox is much better than the one in the Mac Pro, having said that the sound coming out of iTunes via the line out is also pretty good, so it's just the conversion from digital in to line out that sucks the big one.

I have bagged myself a little set of Bose powered speakers from eBay (I know I know Bose are over priced and rubbish). They are quite old, about 10 years I think, but the sound is really good, maybe a little too good

Cheers

Cris.