Mains hum is what you get if items are too close to each other, your connecting cables have been damaged or work loose, or you create an earth loop with a new item.
Yes, got a sonos connect. Set everything up and now I have mains humm when using the sonos. When I switch to another input on my pre-amp, no mains humm. I use the manufacturers cables for power into 2 merlin mains blocks.
Why do I get this only when using the sonos ? Any ideas ?