I have had stuttering audio for over a decade so it will probably be sorted out any day now.
If you have old Pegasos it can stutter when gfx acceleration is used. Known hw bug.
But it can also stutter if playback is done from GUI task. AmiNetRadio or Sid4Amiga don't stutter. No idea how it is done in OWB...
Edit: although I just remember that I got complaint SDL has stuttering audio. It is not stuttering on my Mac (G4) so maybe it could be related to specific audio drivers or even just G5 after all...
