I'm working on a piece for full orchestra in Fin2005 w/GPO Studio and my poor 1.42 GHz Mac mini can't handle all those instruments. I want to try reducing the sample rate to 22.05 kHz to give the mini a fighting chance at playback, but doing this kills my sound module (M-Audio FireWire Audiophile).
Seriously -- if I change the sample rate in GPO Studio to anything other than 44.1 kHz, the FireWire Audiophile stops outputting sound completely, not just GPO sounds but audio from any other app as well. (The MIDI I/O still works, though.) When I click on a note in a GPO Studio Player, the level indicator at the right of the window stays completely black.
Changing the audio driver to "Built-in Audio" does "fix" the problem, in that the GPO sounds do play through the mini's headphone jack. Except (A) the FireWire Audiophile won't output any more audio until I restart the computer, and (B) my speakers are hooked up to my FireWire Audiophile, not the headphone jack on my mini!