Thanks to Gordon Rankin from Wavelength Audio, producer of very fine USB DACs, a temporary workaround has been identified for the iTunes version 7.5 problems discovered by Benchmark Media. This workaround is simple, but kind of annoying for those of us who switch between 16/44.1 and 24/96 music. Maybe I shouldn't complain, at least it will work until Apple releases a fix.
Here is a quick reference sheet:
1. Close iTunes
2. Open the OS X AudioMIDI utility
3. Set the sample rate to match the sample rate of the music you want to play.
4. Open iTunes and play the music.
What about those of us who want to switch between 44.1 and 96 KHz? Go to step 5.
5. Keep AudioMIDI open and make the appropriate adjustments on the fly with iTunes open and it will work fine.
There you have it, pretty simple isn't it.
Additional information can be found on Stereophile's Site