DirectSound / WKM audio-stream duplicator/format conversion

I need a low-level Windows Kernel Module or similar-level customisation of our embedded XP build. Take the example of a motherboard with HDMI out. ? In windows, there will be 2 soundcards (1 is a 'virtual' device for sending audio over HDMI, the other might be 'Realtek HD Audio Out'). We have PowerDVD (or any similar video software) playing back a DVD, the audio is DolbyDigital or DTS 5.1, and it is sending audio to the HDMI-associated audio device. I need OS-level adjustments so not only do you get digital 5.1 sound over the HDMI audio device, but also downmixed, 2-channel stereo over the 'Realtek HD Audio Out' audio device. ## Deliverables The deliverables can be discussed following the requirements analysis phase. ? It probably won't involve any specific installable program, as due to my own research, I believe the solution will involve a system-level kernel or system driver change.