I just played through Company of Heroes on this PC (E8600 X1950XTX Xfi 2G), excellent game, great audio. Xfi over optical into Onkyo receiver, 5.1 audio out. No problems with this game, or any other games.

I installed the add-on, Opposing Fronts and the audio is terrible. Really low, and nearly all in the center channel. 5.1 system is working fine in the creative software.

Any ideas on why the huge drop off in audio between the vanilla game, and the Opposing Fronts expansion?