Sony STR-DH590 Operating Instructions Manual page 20

When the Audio Return Channel (ARC)-compatible HDMI jack on the 4K TV is
not compatible with HDCP 2.2
4K content copyright is protected by HDCP 2.2. To enjoy 4K content, connect the HDMI jack
on the receiver to the HDCP 2.2-compatible HDMI jack on the TV using an HDMI cable.
In this case, the TV sound cannot be sent to the receiver using the Audio Return Channel
(ARC) function of the TV. Connect the optical output jack of the TV and the OPTICAL TV IN
jack of the receiver using an optical digital audio cable.
Audio signals
HDMI cable (not supplied)
Optical digital audio cable (not supplied)
GB
20
TV
Audio/Video signals
HDCP 2.2-compatible
HDMI jack