I had good sound for a while with FC3, and after some updates (don't know specifically that that is what the problem was)
sound became distorted with master set to fullI could turn down pcm a bunch and full master was no longer distorted, but I
could leave PCM full and turn down master just a little and sound was no longer distorted.
Seems to be some overdrive.
BTW, it has carried through to FC5. Happens on all sound SWF, WVM, WAV, MP3, games (I guess WAV). Gotta have master down just a little.
Now, I'm not playing through quality speakers, but I noticed the same thing on a friends system connected to his home
theatre with FC4, (and I remember his sounding good at one time).