I have same sound problems like Paul, sound is terrible and choppy. Here my config:
Geforce 2 GTS 64mb
This should be more then enough to run every emu. I did all above but no change. Only thing not mentioned is that when I press F12 the sound gets perfect but when I return to game it gets choppy again.
I tested Lotus Trilogy, Thomas Tank Pinball and some others but always the same problem.
Somebody solved this?