Xbox 360 with VGA cable, optical cable output hooked up to X-FI Platinum optical input on front bay. I can get audio (5.1) on games, DVDs and video files with 6 channel audio configuration. However, in 2.1 videos such as the Xbox 360 intro when turning it on, videos from the Zune marketplace or any 2 channel video file I place on the hard drive or a USB drive, won't produce any sound. However, if I hook up the RCA (white+red) audio cables that are on my VGA Xbox cable to the auxiliary input in my X-FI, I do have sound. I would use this setup with both optical and RCA cables connected to X-FI, however in 5.1 sources such as the Dashboard or any 5.1 game or video, I get duplicate sounds from both audio cables which is annoying.
I tested this on my home theater receiver with optical cable being the only audio cable coming out of my 360, and worked perfectly. So, it's not my 360, its the X-Fi which in some way is not detecting 2 channel sound from video files. I have looked for all possible settings on my Win7 configuration and can find nothing. Interesting point, music files do play through optical cable on my X-Fi.
So, is there any way for X-Fi to detect the stereo audio source from 360 through the optical cable when playing videos of this nature?
I'm running Win7 Home Premium 64-bit, freshly installed a day ago with up to date drivers.
Based on the fact it works for a HT system and for RCA, I think that the Optical output is sending out a Dolby Digital signal, which teh X-fi can NOT decode. As such, any audio that uses Dolby Digital instead of uncompressed 2.0 will not output properly.
A quick way to test would be to use the SPDIF out of the soundcard to a HT system [which can decode Dolby] and see if you get audio out of the HT system.