This isn’t really a question, but just wanted to post my random scenario in case it helps save some other Sonos users some time and frustration. 

I recently ran into an issue where my Arc surround set up was randomly muting, requiring me to back out of the app I was using while watching my TV and start it over again, only to have it happen again with no rhyme or reason to it. 

My full setup is an Arc, a Sub, two Play Ones, and a Connect with a turntable connected to it through a preamp. The other thing to note is that I have this exact same set up in my living room and in my basement. I have an LG C1 in the living room and a CX in the basement, both connected to Apple TV 4Ks.

I assumed the random audio loss had to be because of a recent firmware update to either the Sonos speakers, TVs or Apple TV that was breaking the chain/handoff between systems, so I spent about a week investigating.

Then I realized that I wasn’t looking at what the Sonos app was actually showing every time this happened. For context, this started happening over Thanksgiving weekend and I hosted - which should have been a dead giveaway, but either way I never thought to actually look at what the app was displaying when the issue occurred, I just put it right back on the TV audio selection or backed out of the app I was using and restarted it. 

It turns out that someone had tried to play a record in the basement, but somehow changed the autoplay setting on the connect to my living room--AND they left the record player on with the needle laying on the record mat. This resulted in the Connect automatically sending its audio signal to the living room set up anytime it received any type of signal - which explained the completely random nature of the living room set up going silent. There was nothing for the basement Connect turntable to actually play, but since it was on, whenever there was any kind of slight vibration that hit the needle it would automatically switch to the living room with the basement Connect as the audio source. 

Once I corrected this everything went back to normal. 

I know this is a very unique situation, but it drove me crazy for about a week, so just hope to help anyone who might find themselves in a similar situation.