Problem with 5.1 DTS missing audio channels?

[Jambolia]

Hi,

I'm having a problem watching a file that's an .mkv with 5.1 DTS audio and I'm only getting some sounds like explosions and the occasional conversation that heavily muted. It's like only 2 channels are being pasted to the TV from the Pi - so I'm missing when people talk and other sound effects.

Xbian is running on a Raspberry Pi, that I've got hooked up to my TV through the HDMI with an optical cable running between the TV and the sound system (5.1 Z5500). The amp is capable of DTS decoding so I don't think it's a problem that end. I've also made sure the sound is set to output through HDMI and that I've ticked the DTS and Dolby capable receiver.

I've looked around the forums and no one else seems to be having this problem. So it's probably something my end, although I've not got a clue what it could be.

Any help would be appreciated!

Edit: I should also say i'm using the latest stable build from the front page.