Power Amp transformer hum - intermittent and increases and decreases in a few seconds

I had that problem once when I lived in a place with very poor power. It was DC getting into the line. I ended up just unplugging stuff when it happened and returning a hour or so later. It was annoying and aggravating. I tried gear to block it unsuccessfully. I was running a tube amp at the time.

I think it's dc getting into my line too. Very frustrating. 

My problem was hum with dryer/dishwasher/blow dryer/fluorescent lights/dimmer switches being used, and that's with a dedicated line to the listening room. The above posters have already given you all the information you need. Hope you get it resolved soon.

Tom

Thx Tom!

You are very welcome! That's what this site is for. Lot's of great people on here! I've been helped many times in the past and am grateful for that and for the chance to help others if I can. 

Tom