My version of PowerDVD is 7 (bundled with my LG HD-DVD + BluRay drive), so I'm sorry if this feature is available in current versions of PowerDVD.
This is why I would like to suggest to delay audio track:
In my HTPC (I'm still mounting it) I use a 42" TV as monitor. You probably know that actual TVs have a lot of image processing... dynamic contrast, trumotion, 600 Hz, and other stuff. That takes a little time to the internal CPU of the TV to process data before displaying the image.
I use an audio amplifier that is NOT the TV itself. The audio amplifier is faster than the TV image processing, so it outputs the audio to the speakers with a 1/4 second of advance.
It's really disgusting to, for example, hear a character talking without any kind of lip-synch between audio and video... or to hear a gun shot before the gun has been phisically shooted by a character...
I hope you may find in this problem a way to make your software a little better.
Regards,