Late to this dance, I know, but I have a MAC MA5200 with no hum issues. I've loved it for 3 or 4 years now. My suggestion? Call an electrician and have him or her check your outlets. Of course, you can do that yourself if you know what you're doing. Please don't electrocute yourself. When dwellings are built, electricians sometimes make mistakes wiring outlets. It's rare but has happened to me. I had 1 outlet in my house with reversed polarity. I'm no electrician but I'm thinking that might be the source of the problem.
McIntosh MA5200 hum
Hi, I bought a three month old Mc MA5200 from a reputable dealer. Brought it home plugged it in and immediately heard a hum. Not through speakers but from amp. Tried plugging it in everywhere in house, same result. No hum comes through speakers but can here hum from amp between songs from 10 ft away. Took back to dealer next day, plugged into his wall direct, no hum. Brought it home and same hum produced. I have lots of other amps and made sure that none of them are humming. Very perplexed. Does this amp not like my AC? I do not use a power conditioner. Any thoughts on what to do next would be appreciated. I could probably live with hum but why should I? Worried that amp might need repair. But again no hum at all at dealer. Thanks for your thoughts.