Battlefield 2 and it's 'sister' game, Battlefield 2142, are one of the few games that include support for the X-Fi and its 128 voice 'ultra-high' mode.  Most people who have this game and an X-Audio already know this: the X-Audio is not detected as an X-Fi:

D'OH.

But, we could use Hardware mixing and the 'high', 64-voice settings, with and without EAX without any issues.  It all worked very well, actually.  Well, almost...

I re-ran this test over several days, about 30 runs, and these are the averaged results.  We usually see EAX perform with little or no performance issues, but here we see a few FPS difference.  Subjectively, the X-Audio is quite a lot better with its effects, with doppler and sounds believably falling off with distance.  It's no comparison to a true X-Fi with all the EAX HD effects, if memory serves, but at least it's better than the test competitors.