Slight hum in my amp. Is this normal?

@gdhal,

An isolation transformer will not pass DC.

oldschool1,

Is this what the inside of the amp looks like?
http://www.studio-22.com/anthem/images/Anthem%20MCA%2050%20-%20Inside1.jpg

If so notice the two toroidal transformers on each side. Pull the top off the amp and check the center mounting bolt and nut for tightness. Make sure the round top plate is seated properly on the top of the transformers. Maybe one of them is loose.

After checking them, to make sure they are secure, power up the amp and listen to the two transformers. If the hum/vibration is still there listen to each transformer individually the best you can. First verify the hum is coming from one or both of the transformers. Is one louder than the other? If so recheck the mounting bolt and nut. Make sure the round top plate is seated properly on top of the transformer.

I was unaware (until I heard about it here and looked the damn things up) of the Emotiva CMX stuff, but it IS less expensive than the Humbuster III, and actually obtainable. Cool.

What jea48 said.  I just didn't want to be an accomplice if you touched the wrong place with your screwdriver.  Let us know what the solution was.

Today I dropped it off at the local authorized service center who has been the only company to work on my amp. Interesting thing, without opening the cover, I put my ear real close to the vents adjacent to the transformers, there are two, one on the left and one on the right just behind the front panel. I could swear the hum sounds slightly louder from the right side making the right side transformer suspect. I used an analog decibel meter using fast and slow response, and it's hard to tell with the slightest ambient sound pressure. It measured approximately 55 dB with the right side maybe 1/2 - 1 dB higher. Are my ears that good? the proof will be in the pudden when the shop gets into it. The owner said he would get in early when it's dead quiet and listen for the hum.
I told him today that the hum is loudest when power is initially applied then quiets down however, I can still hear the hum from 10 ft away when the room is quiet. Of course when a program is playing, the speakers drown it out so It's inaudible. My Integra DTR-50.3 AVR, $700.00 retail has always been dead quiet. Certainly a $4000.00 retail Anthem A5 amp should be as well.
Lets see what they say in a couple days. Stay tuned!