I received a Supreme FX II Sound Card with my ASUS Rampage Formula motherboard. I also have an Auzentech X-Fi Prelude sound card that I will be installing in this computer as well. Can I install both cards and have ATC on my headset and all other sounds on my main speakers?I think the Supreme FX II card is based on the onboard sound of the motherboard, but I am not sure. Just curious as to if anyone has tried this.

Yes you should be able to. I'm currently using my SB X-Fi for sound in FSX and the onboard sound on my motherboard for ATC. A USB headset also works well for ATC.