Sony STR-ZA810ES Manual page 48

Speakers
Amplifier/receiver
Audio cable (not supplied)
Audio signals
Note
Only audio signals from [USB], [Bluetooth] (only when in BLUETOOTH RX mode), [Home Network],
[Music Service List], [FM TUNER] and audio signals input from AUDIO IN jacks are output to the
Zone 2 speakers.
External digital input from OPTICAL IN, COAXIAL IN and HDMI IN jacks cannot be output to Zone 2.
[38] Preparation 4. Connecting audio-visual devices and the antennas (aerials)
Connecting another amplifier or TV in the HDMI zone
HDMI input video/audio signals are output in HDMI zone using the HDMI OUT B/HDMI ZONE
jack of the receiver.
When connecting only to a TV
When connecting to another amplifier