That's an issue I'm working around at the moment, just added it in case anyone has a fix!
My issue now is that I want to start recording my mic input in a seperate track so that I can edit my voice seperatly to try and remove and distortion or quiet areas. I tend to be fairly loud in my recordings so I want to try and edit it to a more level listening experience. After speaking to the devs of D3D, I've started recording in AVI2 instead of WMV, the audio is Raw PCM instead of MP3. We've verified that there are two seperate audio tracks and can listen to both of them seperatly with MPC-HC which is the media player that comes with D3D. If I play the AVI2 recording in Windows Media Player then both audio tracks play together and it sounds fine. When I open with powerdirector 13 however I can only hear my mic recording, not the game sounds. For some reason it's not coming up with the other audio track and I can find no reference as to where it might be.
The reason we've used these settings is because the developer of D3D is not familiar with CPD, however he does have experience with Sony Vegas and said that Sony does sometimes have issues with seperate tracks when recording in MP3.
Any assistance would be fantasitc, because I really want to be able to improve my voice audio, and I can't do it when recording into the same track as game audio!