Keith Jarrett, The Koln Concert, downloaded as 92 kHz from HD Tracks.
What are you using to play that?
I d/l it, tried my SB Duet, it complains the format is unrecognized.
Using Winamp on my htpc, it plays fine.
I decode flac at the media server in squeezecenter before playing, everything else is default settings, could that be the issue?