How do I make MPC-HC play 5.1 audio?

I have a bunch of 5.1 surround BD disks and rips I want to play with my PC through it's optical SPIDF port to my Pioneer VSX-523 AV receiver, but MPC-HC refuses to play anything but PCM and 2.0 stereo. Meanwhile, Windows Media Player can play the same files and disks in 5.1 Dolby Surround. I don't want to use Windows Media Player, I want to use MPC-HC.

So:

How do I make MPC-HC output more than 2.0 audio?

My motherboard is an ASUS P6T Deluxe, and I'm using the on-board sound chip, which is an ADI AD2000B 8-channel High Definition Audio CODEC (or at least that's what the motherboard manual said).

Little help?

You need to enable S/PDIF passthough/bitstreaming in the audio decoder.

When using ffdshow:
ffdshow audio decoder options > Output > Pass-through

When using LAV audio decoder:
LAV Audio decoder options > Audio Settings > Bitstreaming

GREAT! Now if only I could get my PC games to do that.  

Thanks for the help.