Surround Sound vs DD5.1 vs DTS5.1 (1 Viewer)

[RetroZA]

TV-Server Version: TV-Server 1.0
MediaPortal Version: MediaPortal 1.0 RC3
MediaPortal Skin: Monochrome 2.2
Windows Version: XP MCE SP2
CPU Type: Intel 2.4ghz
HDD: 20gig IDE & 500gig SATA
Memory: 1GB DDR400
Motherboard: Intel865G/ICH5
Video Card: Geforce FX5200
Video Card Driver: Nvidia 175.19
Sound Card: Realtek ALC650
Sound Card AC3: Optical S/PDIF out
Sound Card Driver: Realtek Avance AC97
MPEG2 Video Codec: MPV Decoder Filter
MPEG2 Audio Codec: MPA Decoder Filter
h.264 Video Codec: CoreAVC
HTPC Case: Aopen XC Cube EY65
Power Supply: 220W
Remote: Microsoft MCE
TV: Sansui 40" LCD (720p)
TV - HTPC Connection: VGA

I recently bought a surround sound set for watching movies and for my Xbox 360. The AV receiver has an optical audio input. I'm running a cable from the pc (spdif out) to the optical in on the receiver. I struggled for a couple of hours, but it looks like I'm getting somewhere. In the decoder settings tab in MP I've set all options to spdif. I've also checked the 5.1 playback options under the movie player (internal player) tab. When playing HD, DVD & movies decoded with AC3, I'm definitely getting surround sound. But how do I know I'm getting DTS5.1 with the HD and DVD's? My AV receiver doesn't show what source it's getting. It's just showing Aux/Opt.

Is there any way to somehow test this?

 

[RetroZA]

So I'm guessing there's now way to check if you're getting DTS5.1 unless your AV receiver tells you you're getting it?

 

[RetroZA]

Ok, so last night I connected my Xbox to the AV receiver and it showed Dolby Digital on the receiver. So I tried playing a DTS movie again from my pc and it also showed Dolby Digital. So at least I know I'm getting Dolby, but why not DTS?