Has anyone managed to get an x-fi to output true 5.1 Dolby Digital/DTS to a receiver? I get sound from all of my speakers but, when watching a suitably encoded DVD (via MCE2005), my receiver is not showing the signal being received as being Dolby Digital or DTS (as it does when watching BBC HD on my V+). My set up is: My PC has an x-fi xtrememusic soundcard, connected to which is the creative digital I/O module (which plugs into the flexijack). This is connected by optical cable to my receiver which is a cambridge azur 540R. I have installed AC3 filter but am not sure whether it is actually being used - when I go through the mce speaker set up (to tell mce I've got 5.1 speakers attached) I do not hear the test tones from the rear speakers (but the fronts and sub are fine). To troubleshoot this, MCE then tells me to configure my DVD audio settings and it automatically brings up an nvidia window (as opposed to AC3) where I tell it that I've got the PC hooked up to a receiver. I run the speaker set up again and still get no test tone from the rears. I have nvidia purevideo decoder installed. When I go into the creative x-fi program within mce it will not let me select the DTS or DPL II options. When I go into AC3 filter and make changes they do not seem to have any effect. I've tried all the different sound modes on my receiver (inculding passthru) but, despite getting sound from all speakers whilst watching a DVD, the DTS/Dolby Digital light does not come on the receiver (which suggests to me that the DTS signal is not making its way to the receiver). The limited surround sound I do get is presumably emulated (DPL?) by the x-fi. Am I going crazy - should the light not come on at all? I've read about people having trouble with getting full AC3 5.1 from avis but never from DVDs on mce. This is so annoying - short of buying a separate DVD player and hooking that up directly to the receiver I don't know how else to get proper 5.1 from DVDs, but I really want to use mce as my DVD player. Any ideas?