I get stereo but not surround sound (TV UE40ES7000Q)

Hi

I'm running Serviio 1.0.1 on a Mac. I use a Samsung UE40ES7000Q connected through an optical cable to a Yamaha YHT-196 Home Cinema Kit (it supports 5.1).

The video works fine, but I get only stereo audio.

I attach the movie profile and the detailed logs.

Thanks!