Well, I did also test if with the very demanding Heroes of Might & Magic II ;-)
But something's happened. The bass from my sub (which never was set very high, usually dialed in to about 1/3 of max on the sub itself), has started to distort rather heavily.
(This even with the master PC volume set to 50% and in both Entertainment, Game and Creation modes, with the speakers set to Full Range or not.)
It definitely didn't do this when I first installed it, so I tried uninstalling and reinstalling the driver, but the distortion remains.
Do any of you with X-Fi Xtreme cards (on Win 7) have experience with this?
UPDATE:
Trying to troubleshoot the above, I also tried installing Daniel K's XFI Support Pack, but couldn't as my anti virus ate one of the files.
And then I re-enabled the on-board audio and realised that the bass distortion wasn't restricted to the X-Fi. So apparently my sub chose to crap out very shortly after installing the X-Fi (as The Knife's Silent Shout with its deep bass was sure to point out).
Good to know, as I was ready to go out and get a Soundblaster Z (going back to the onboard was a very noticeable reduction in quality, distortion aside - which is only from the sub). So it seems I need new speakers instead.