Hi @Loshkai
Thanks for your post!
Sorry to hear of this issue your are having when trying to use headphones with your TV instead of the Arc Ultra.
You are taking the correct steps - to prevent your TV from switching to the connected audio device, you do need to disable HDMI-CEC (which LG call SIMPLINK) while you are using the headphones. However, if your LG TV will not “listen” to you when you change this setting, I can only recommend that you get in touch with LG to report as much - only LG will be able to alter this behaviour.
The only other option I can think of is to use Sonos Ace headphones, which would connect to the Arc Ultra rather than the TV, meaning the SIMPLINK setting can stay on.
I hope this helps.
Another approach would be to install a CEC blocker. This will allow you to keep SIMPLELINK active, but it will never receive any transactions from SONOS. You’ll then need to enable IR Volume control for ARC ULTRA.