Hi,
I've two scenarios at hand now: one involves a Windows 7 guest with -soundhw hda, the other is my Musicpal (do you still have a firmware image at hand?). Some Linux guest here with identical configuration like Win7 does not show any problems in polling mode.
Noteworthy difference between linux and windows 7: Windows 7 uses a pretty small ring buffer (~ one page, where 20ms sound data fit in) whereas linux uses *alot* more, 128k or so.
That makes win7 guests quite sensitive to latency issues, be it in the audio subsystem or elsewhere. For example bulky screen updates with the non-threaded vnc server are enougth to cause audible glitches in audio playback.
HTH, Gerd
