I can't hear the voice effects dialogue. I've turned music and SFX volume way down but the voice is still too low to distinguish what is being said. Running Vista 64 on EVGA X58 Classified mobo with onboard sound configured for 5.1 headphones.

Out of curiosity, do you have your sound settings in Windows set to surround sound or 5.1 of some sort? Maybe try the sound settings on stero or mon to see if that does anything for it. I apologize if this is something you've already tried.