New house, new LG TV, home cinema kit in storage so use internal speaker. Works fine. Connect Bluetooth heaphones, they are fine too, automatically muting the speaker. Sony STR-DA2400ES amp out of storage. Sky box now connected to Sony amp which then connects to LG TV via the same HDMI input as previously. Lovely sound - no headphones. The TV recognises the headphones switching on and asks whether to connect. Click yes and TV says headphones are connected - but no sound. Going through the "Sound Out" section of the TV settings it's clear that it makes no difference whether "Internal TV Speaker" or "Audio Out (Optical/HDMI ARC)" or "LG Sound Sync / Bluetooth" is selected. Why is this? What's arriving at the HDMI input from the amp that's different from the Sky box? How do I get headphones working? The TV is a 55UJ750V, bought it from John Lewis. The label on the back says so. I can't register it with LG though as their website says there's no such thing.