S/PDIF digital audio not doing 5.1 digital surround

[JeanGoulet]

Got a brand new ASUS laptop, has a 1920x1080 screen and Bang&Olufsen speakers and blu-ray for portable use, and native S/PDIF interface plus an HDMI interface (great for home theater use). I chose that laptop because of those features.

My goal is to have video through HDMI (I have a DVI-only speakerless HDTV), and audio on the S/PDIF interface (going to an audio-video receiver).

Splash Pro is providing fine video, but not audio. That's because it's only in stereo. I am expecting dolby digital 5.1.

In the audio settings in Splash Pro, it claims to allow "S/PDIF" (and it accepts that selection) but leaving that screen and returning to it, brings it back to Stereo. And the Audio/Video Receiver I am using stays in stereo the whole time, and my ears clearly hearing nothing more than front left+right.

Of course I checked that everything in the chain of equipment can do DD5.1:
- the source I am using is an MKV that is definitely DD5.1, since it works on another (Vaio) laptop.
- the AVR is DD5.1 from TOSLINK, as the Vaio brings the AVR to DD5.1
- And the final "most important" verification is that the ASUS can indeed generate DD5.1 from its S/PDIF TOSLINK 3.5mm connector, with the appropriate "optical mini-plug to regular TOSLINK" adapter, to the AVR, just by doing the 5.1 test in the Windows 7 audio "playback devices" GUI.

Which leaves what as the culprit? Splash Pro. Quite disappointing. What is the solution?

[Ghost]

Whats your laptop model? We will try to reproduce problem in our labs.

[JeanGoulet]

Whats your laptop model? We will try to reproduce problem in our labs.

Asus N53J Series (N53JF-XE1 with 1920x1080 screen, Geforce GT 425M, Core i5-460M, Realtek High Definition Audio).