I will have a try. Let’s check if I can send 4K 120 Hz VRR HDR with Atmos to the Tv through a hdmi 2.1 optical extender and the get the sound up to the AVR running Atmos. So many things that can fail\n\nNot sure I understand why you need 'optical extender' and what exactly this is. With eARC HDMI cable video and sound goes through one cable. This actually is like a in\/out for both TV and receiver.