Static noise over optical audio to Sonos Beam when using AppleTV 4 only

I have an AppleTV 4th gen (not 4K) that I have hooked up to my Sharp TV. I haven't had problems with this setup, but recently I bought a Sonos Beam and connected it to my TV via the optical audio port (the TV's a little old so no HDMI ARC). I've noticed that when I watch TV for a bit, something happens and the sound coming from the Sonos turns staticky and crackly. This seems only to happen with the AppleTV, as opposed to playing music or using one of the other TV inputs. I also think it's the fault of the AppleTV because, using advice from this thread, I've been switching the video output from YCbCr to RGB High or futzing with the resolution on the TV, and whenever it switches, the audio resets back to normal.

The noise switchover seems to happen randomly, but after I'm probably about 30 minutes into a TV episode. But it's happening constantly enough that it is a pain to have to keep resetting the output just to get things to reset. I've tried the suggestions on the thread that I referenced above and at most they're stopgap measures. I know that I'm not the only one who has had this problem, so I'm wondering if there have been any better solutions that have been advanced since that thread (which was about the AppleTV 3...in 2012...), if buying an AppleTV 4K might be a potential solution, or if I should just set fire to the whole thing and start over (only my wallet tells me that's a dealbreaker!). Any suggestions would be greatly appreciated, before I have to go and buy a Roku or Fire Stick...thanks!!