Samsung LE32C650 DTS passthrough

[Auzman]

Hi everyone!
I haven't been able to make the dts audio to pass through a Samsung LE32C650.
My setup is made of a raspberry with xbian alpha5 connected via hdmi to the TV set and an AVR (yamaha rx-v450) connected via optical cable to the TV set.
If I use the tv built in media player I can get the dts to work via the optical audio connection. To do so I connect the TV via lan to a dlna media server (meezmo) and everything is fine.
If instead I use xbian via SMB shares and playing the same file, there is no way for me to get the dts to work.
In the tv menu I can only choose the PCM streaming and the "dolby digital" is grayed out.

Have you any suggestions?

Thanks!