Are any of your SONOS units wired to the network?

hi buzz, yes port is wired to Lan, and port connected to turntable project

Are you using a voice assistant on the Sonos Arc, such as Alexa? If so, perhaps goto the microphone on the Arc and see if toggling it ‘off’ stops the audio drop issue?

hi Ken, no voice assistants are active..

I wasn’t sure from your description if the audio was ‘ducking’ on your Port every now and again due to the mic being activated by interference from the TV .. Having ruled that out, maybe try this..

In the Sonos App goto the Port settings in ‘Settings/System’ and set a greater ‘audio delay’ buffer (try 113ms (medium) to begin with) and see if that perhaps helps to resolve the matter.