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

Thx E. I'll try the breaker solution after work.  

Hums every time the amp is on?  Yes
Hums no matter the time of day? Mostly in morning and sometimes at night. Very sporadic 
Hums ever since owning the amp? Yes
Any changes to system/house electrical devices? None since purchasing the amp. 

Thx lowrider.  Amp is SS and hums only thru transformer. Hum goes up in volume and then down in a cyclical type pattern.  

Thx Tom!

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

Agree.  I did try a cheater plug to no avail.  Thx to all for their input. It is much appreciated. 

I'm using a Harman PA5800 that I recently purchased from a friend. I've had it for less than a month. The transformer is not loose, and the amp appears to be in excellent condition.  I also moved the amp to another location in my house and the amp is silent. From everything I've read on the net, I'm lead to believe it is DC Offset related. 

I don't have a multimeter.  This is my basement Home Theater and I do have cheap LED light bulbs in use.  I turned them off to see if I still get the hum. I'll check it over the next few days to see what happens.   Yes, that's the picture of the amp.

Ken:  yes, very frustrating. Hum is just coming from transformer. 

Jea48:  thx for ideas. I'll look into them.