First, I'm glad to find this topic because I've the exact same problem. Second, sorry for my English, but I'll do my best.
The first fact that I have a SR7010! So the problem also exists in the following model.
For me the noise and the lack of sound was started at the front right top. Sorry, the configuration is 7.1, (5.1 + two front top speakers; only Wharfedale speakers). It was on the first day at the audyssey setup!
I've checked the cables and the setup finished fine. Heart attack has gone...
Few weeks later the left surround started that popping noise and then I got the muted channel. Some very little sound came out from the speaker but You know it is not good.
Somehow (I really don't remember) maybe with the change of the cables this problem has never occured... at the left rear.
The problem moved to the center speaker and now to the front right. Today the receiver is in service but they could not reproduce the problem.
I've checked all cables all connection points, cut all banana plugs, peeled all cables again. Firmware upgrade, Factory reset. Nothing worked.
- There were times when not only one channel was affected. Center with the top left mostly.
- When I touch the backplane of the receiver and try to screw the proper channel's speaker terminal it solves the problem! For one day.
Next day hardly I can screw again a little bit. Loosening? Or I get stronger. But I can not imagine that there isn't any connection.
- I can reproduce the problem with cable TV, Media player, Spotify, etc.
- After powering On for the first (on a day) the problem comes after a while. The first 10 minutes is OK (Volume 40). Heating problem???
I am suspicios of the two top speakers too, so tomorrow I wiil check Maco07's suggestion.