I had the same issue with an 85" samsung with the external box and the snap arc balun. We eventually gave up and moved the sonos amp to the TV and jumped the speakers back to the rack and out to the in ceiling speakers. That solved the issue. PIA though.
I'm Not an engineer, but I play one on TV. My handle is Tweety but I have nothing to do with the organization of similar name. I just had a really big head as a child so folks called me tweety bird.
