So the sound effects are working fine but I can't hear any music to speak of.

Has the music been completely stripped for this release?

I'm afraid I can't help, but knowing which game you're talking of and having some information about the your system may help.

Music is missing from my download of DK2, which I got yesterday. Also, there is no mentor voice in game. I can hear "One, two" when setting the voice volume in the sound options. There are "speech_..." directories in the Sfx directories. Other sound works fine.