Sony Bravia XBR-75X850C Reference Manual page 18

XBR-49/43X830C
Rear of TV
* The optical connection is only needed for home theater system that do not support ARC
(Audio Return Channel) when connecting with HDMI.
Set the speaker settings to audio out, press HOME, then select [Settings]  [Sound] 
[Speakers]  [Audio system].
Set the HDMI CEC settings on the TV and AV receiver to allow for system audio control for
ARC connections.
18
US
Side Panel
*Optical Connection
SD Cable Box or
SD Satellite Receiver
Cable/SAT (Dish)
or
Home Theater System
Cable/Antenna
Blu-ray Disc/DVD