No Dolby Digital with MPC

[McWalt]

Hi,
I just installed Windows 7 (64bit) and now I have two new problems concerning 5.1 audio which I did not have before with Windows Vista (64):

1) MPC: Media Player Classic plays all stereo sources in stereo, while Windows Media Player or VLC Player convert the signal to DTS. Movies with 6 audio channels are played just fine. This means that I can't have 6 channel audio experience for 2 channel movies with MPC

2) Windows Media Player: Volume control does not work for all Dolby sources (6 channel audio). If I watch stereo it works fine, if it is a 6-channel source there is always a fixed volume.

How can this be? I am a little bit conservative, that's why I would not like to switch from MPC to VLC.
Maybe somebody has any idea - please.

Thanks!

[McWalt]

I could solve Problem 1, if somebody might have it as well:
I had to activate the "Dolby decoder" in the ffdshow audio preferences (for 32bit and 64bit, since I have installed both Kazaa Lite codec packs).

The second problem keeps to be a mystery for me.