Tu tele es una de las muchas que cuando le llega audio de un reproductor la convierte a stereo y por eso solo te la saca en 2.0

Sacado literal de tu manual:

●● A home theatre system that has been connected to the TV using an HDMI cable and an optical
cable supports 2-channel audio only. However, the home theatre is capable of supporting
5.1-channel audio from digital broadcasts.
●● To listen to 5.1-channel audio from an external device, connect the device to the TV via an HDMI
cable and the device's digital audio output connector directly to the home theatre system.

Así que o cambias de "home cinema" o de tv