Down filter DTS etc. to DD5.1 for sound bar connected with HDMI

Hi everyone, I just got a new sound bar (Yamaha YAS-105) which only supports Dolby Digital 5.1 (AC3, I think) and I want it to smoothly transcode all of my DTS or newer audio to a multi stream AC3 in both MPC player from the latest K-lite mega pack, VLC and Winamp, or rather, if possible, just in general. If I play something thats DD5.1 in K-Lite's MPC it neatly picks up the audio and displays it as DD on my sound bar, same thing goes for DD5.1 in VLC etc. but as soon as I play something in DTS or higher there is no audio. I've been googling and tweaking the settings already and after messing around a bit it does play sound through MPC but none of my Dolby lights light up on my device and it doesn't sound like 5.1 either, the weird thing is that no lights go on, not even the PCM light just the TV light is connected and it gives a sort of stereo with subwoover sound (so 2.1). If anyone can help me out I'd be very grateful, I know it's possible because it works with media boxes as well, I just can't get it to work on windows... Any extra info, I have an Alienware X51 RC1, Soundbar is a Yamaha YAS-105, like I said it's hooked up via HDMI to my TV and my TV through a Digital optical cable to my soundbar.

I figured, why not try to use the Bluetooth connection in it to see if that helps.I have a little Bluetooth 3.0 dongle so I connected that to my PC, it found my keyboard and stuff just fine, also found my soundbar, added the soundbar and it finds 2x COM devices (a COM4 and COM5 for bluetooth) but doesn't find 2x Bluetooth devices so it shows up but doesn't work... can anyone help me with this?