Jedi Outcast Audio Problems

Howdy all. I've got a Herc Fortissimo II Sound Card, and am having a little issue with Jedi Outcast.

If I enable EAX, the sound volume drops by about 200% and I have to blast my speakers to get it back up again. Anyone know why? The quality is much better with EAX on, but the volume drops a whole lot.

Thanks