I have a Sonos Port connected to my Denon AVR-X3500H. I had an odd problem: when playing music from any of my sources my Denon would go into protect mode after 10 or so minutes. I tried using the coax digital output and then the RCA analog outputs - same problem.
The Port was located on the top of my Salamander rack with the Denon on the first shelf below. I moved the Port to the bottom shelf of the rack and the problem seems to be resolved.
Anyone with a similar experience? What was your fix?