my fault.. didnt see gtx 470..
but.. thats your problem. the gtx 470 does not bitstream hd audio.
From renethx- http://www.avsforum.com/avs-vb/showt...3#post19553213
its about a year old - but your card is listed as a non streamer...
AMD and Intel support HD video playback and HD audio bitstreaming. Clarkdale lacks proper 23.976Hz playback, however. Higher-end NVIDIA's solutions (GTX 465 and higher, GTX 570 and higher) do not support HD audio bitstreaming.
Here is a summary of audio formats supported by various PC video/audio solutions.
Dolby Digital and DTS bitstreams, and stereo LPCM
Every motherboard's onboard audio codec (via optical or coaxial S/PDIF connector)
Every AMD 760G/780G/785G/790GX/880G/890GX chipset motherboard (via onboard HDMI)
All the solutions mentioned below
Multichannel LPCM over HDMI
Every ION/GeForce 8200/8300/GeForce 9300/9400 chipset motherboard (via onboard HDMI)
Every GeForce 210/GT 220/GT 240/GT 430/GTS 450/GTX 4xx/GTX 5xx graphics card
Every Radeon HD 4xxx/5xxx/6xxx graphics card
Every Intel G41/G43/G45 chipset motherboard (via onboard HDMI)
Every Intel Core i5/i3 (Clarkdale) processor (via an H55/H57 chipset motherboard with onboard HDMI)
Dolby TrueHD and DTS-HD High Resolution Audio/Master Audio bitstreams
Every Radeon HD 5xxx/6xxx graphics card
Every GeForce GT 430/GTX 450/GTX 460 graphics card
Every Intel Core i5/i3 (Clarkdale) processor (via an H55/H57 chipset motherboard with onboard HDMI)"