You can use any headphones you want with X-Fi dude. When you get your X-fi try it out with a cheap pair of HP's. That's one of the great things about X-fi... The CMSS 3D makes normal Stereo headphones sound like 5.1 surround sound headphones.... It's pretty damn cool.
DJ-CHRIS needs to hear X-FI with Z-5500's... I think even he would be impressed.... LOL...