Have just posted this on a couple of other forums but thought you lot might be interested...

Stumbled across this almost by accident.

After installing my Prelude the other day, I noticed that MacroFX and Elevation filter couldn't be enabled in 5.1 mode so I assumed they might be headphone only. Having said that, I was sure I'd been able to use them with my surround speakers on my old Xtreme Music.

As for what these do, elevation filter is supposed to simulate a z axis by altering sounds above or below the listener. MacroFX is supposed to simulate very close sounds.

My old Inspire 5700 speakers only had a 4.0 analogue connection though. I did some digging and turned this up with Google:
Frontlines Warfare :: Interview with Matthew Harwood
5. Will Frontlines: Fuel of War take advantage of X-Fi technology?

That answer is a bit complex so I had a programmer help me with it. The game supports OpenAL, which can take advantage of X-Fi features. Specifically, for altering your speaker set ups - 5.1, 4 speaker, 2 speaker, or headphones or whatever your hardware supports. Also, make sure that you are in Game mode. This is required to get EAX 4+, MacroFX, and ElevationFilter. For 2 or 4 speakers, make sure you are sitting in the sweet spot in order to get the correct HRTF effects.

CMSS-3D, MacroFX, and ElevationFilter, is irrelevant for OpenAL games when you have 5.1 or more speakers. Unfortunately, this also means that you don't get MacroFX or ElevationFilter effects with 5.1 or more speakers. If you have 5.1 speakers, I'd suggest trying a OpenAL game in both 4.1 and 5.1 mode to see which you like best. You won't be able to get MacroFX and ElevationFilter with 5.1, but the sweet spot may be more forgiving due to lack of HRTF with 5.1 or more speakers. Also you still get reverb and other effects from software rendering. Hardware just gives you the multiple speaker output (more then stereo) and the other post processing effects that your hardware supports like EQ etc. Again, you have to experiment with what you like best.
I've been using Dolby Headphone on the Victor SU-DH1 to simulate 5.1 speakers with a DDL signal from the X-Fi Prelude. Changed some settings to get it to output 4.0/4.1 and fired up Bioshock (changing the in game setting to quadrophonic). Set MacroFX and Elevation filter both to auto.

Well blow me down if I can't hear the difference. Elevation is working. I think MacroFX is working, with the protagonist's breaths feeling really close.

So if you're gaming on an X-Fi with a 5.1 or 7.1 setup, I advise you to try 4.0/4.1 (or even stereo) and see if it makes a difference.

I may be wrong about this, but I think they might get enabled by default on the Creative X-Fis, even for 5.1+ speakers. I tried out an OEM xtreme music before the Prelude and if I recall correctly I could enable MacroFX and Elevation filter in 5.1 mode. Wonder whether it works in 5.1 mode or autoswitches to 4.0/4.1? Maybe someone with a Creative card can let us know?

Not sure whether EAX 4/5 or OpenAL are requirements or not. If people want to try they would seem like a good place to start though.

A few of the OpenAL games with EAX 4 and 5 include:
Battlefield 2
Battlefield 2142
Frontlines: Fuel of War
Mass Effect.