5.1 surround sound bitstreaming from GeForce 430 to receiver not working.

[Twisted.Raven]

First off this issue has been bothering me for some time, I've scoured the internet looking for solutions with no avail. I built a HTPC and picked up a Sony surround sound system to compliment my Sony HDTV. My issue is, I can't for the life of me get 5.1 to output over HDMI. Here is my setup:

HTPC:

MSI 880GM-E43 AM3 AMD

AMD Athlon II X3 450 Rana 3.2GHz

EVGA GeForce GT 430

Sony KDL-46Ex700 HDTV

Sony BDV-E780W Surround Sound.

Connection is simple enough, using just HDMI:

[HTPC] --> [E780W] --> [HDTV]

I'm using windows 7 x64. I have all of the latest drivers for graphics card and mobo. In the sound options for windows 7, under playback devices, the receiver shows as SONY-AVAMP. Normally where you would select stereo, quadphonic, 5.1 surround, 7.1 surround, the only option available is stereo.

When testing the connection under the configuration options, the right, center and left play correctly, the rear left plays through the front left and same for the right. I've tried PowerDVD 12, with the audio options set to "Non-decoded Dolby Digital/DTS audio to external device" with the same result. Also tired TotalMedia Theatre 5, no go. Tried re-installing windows about a dozen times. Turned off HD audio on the mother board, etc, with still no luck.

It seems it could possibly be a problem with the EDID of the TV, which dictates to the graphics card the max speakers it can accept, but from the graphics card it's connecting into the receiver.. not the TV? I've tried turning the speakers on the TV from "TV" to "External" with still no luck.

I'm at a complete loss, does anyone have any suggestions I could try?