I have a Sony Vaio XL201 with Vista Media Center outputting sound via an SPDIF optical cable to my amp. My Vaio uses the Sigmatel High Definition Audio codec.
I have found that when you go into Control Panel and Sound, I have configured for SPDIF output only, but there is no settings for 5.1 etc. In VMC itself, I have set the speaker settings to 5.1.
My amp shows on the front panel what channels it is receiving.
I play an MP3 and the amp shows sterio.
I play a stored .mkv video file and the amp shows 5.1.
I then play a DVD that has 5.1 sound, but the amp only shows sterio.
I then play that same DVD using Arcsoft Total Media Theatre software and my amp shows 5.1.
And all DVD's with 5.1 sound also do the same in VMC - only sterio.
Can anyone explain this? It is driving me nuts this.