Hello I just picked up the Xfi platinum and I am wondering what do I set it on? I have a pair of Sennheiser PC160SK which are supposedly able to digitally recreate 5.1 surround sound. So do I set my sound card to 5.1 or headphone? When I use the test on the creative software it only works on the far left speaker but sound comes out of both of the headsets. Any Ideas?