Slight hum in my amp. Is this normal?

Picked up my amp today and at the shop it seemed dead quiet however, there's ambient noise in the shop. According to the owner, early in the morning he heard nothing. It was dead quiet. After getting it home I spent the evening re configuring all my wiring taking care no power came in contact with any signal wire. here are my results as I emailed the shop owner:

Hello Morris,
It’s about 10:20 pm and everything sounds great however….
Remember I said that the “hum” could be heard from 10 ft away? Well I just unplugged and powered everything off one thing at a time and here’s my findings; What I can hear from 10 ft away is coming from the speakers. Yes there is a very slight “hum” in the amp and it’s also coming from the speakers. If I disconnected the interconnects from the preamp, no change. Of course since the power is off on the preamp and no signal feeding to the amp. Then I disconnected all the speaker cables and yes there is a “hum” or “buzz” in the amp. It has to be very quiet in the room to hear it.
This “hum” or “buzz” is not only in the amp but sending it through to all 5 channels. this explains why I can hear it from my listening position. I have a surround sound “hum” or “buzz”. So yes, the “hum” or “buzz” is in the amp and the amp also sends this noise to the speakers, all 5 channels. Could it be a bad ground causing this? Again if its the ONLY component with power connected, how could that be? Btw, there is no other electrical device on in the house other than an incandescent lamp for light. I tried powering it straight from the wall, using the Torus TOT MAX, and straight from the wall with a Emotiva CMX-2 Precision AC Line Restoration and Common Mode Filter System without the Torus.
I can only suspect it’s a component in the amp that is defective common to all 5 channels.

Any ideas anyone?
As a last resort, I will send it to Anthem in Canada. Being a current item, they will have all the components to trouble shoot with. It's just expensive to ship from California to Ontario, Canada. May be my last and only option.

oldschool1, I can't remember.  Did you ever try a cheater plug just to see if it eliminates the hum from the speakers?  Not to use permanently, but to narrow your investigation?  In any case good luck in finding the issue.

From a photo of the A5 back panel, it looks as if the IEC inlet is only two prong - not the 3 prong w/ground. (It’s difficult to tell from the angle.) If this is correct, then a cheater plug won’t do anything. A hum coming out of the speakers (ever how many are hooked up to the amp) is usually caused by a bad ground somewhere in the system - or a culprit in the house wiring. Sending the unit back to Canada won’t fix the problem. Here are some possibilities:
- A dimmer switch, old kitchen/bathroom appliance or a bad fluorescent lighting ballast is sharing the same circuit. Have you tried turning everything off - except the system?
- Try running a 24 gauge wire (a la Home Depot) from a screw on the amp chassis to the outer sleeve of any RCA connector on each your source components - one component at a time. See if the hum goes away.
- The power cable to the amp is wired backwards between the hot & neutral on one termination - the reverse of the other termination. Have you tried other power cords?

I tried a different power cord. If it were a ground issue, wouldn’t running it through a power conditioner such as the Torus correct it? Also, the Torus is plugged into the outlet by the left channel and I tried plugging directly to the outlet by the right channel. And the electrical connection is a two wire AC connection to the power source.

No, the Torus is not a miracle cure. The electrical outlets by the left/right channels may simply be on the same circuit. The two prong IEC means that there is no connection to ground. This may or may not be the problem. Try grounding the amp via an external wire as mentioned above. See if the hum goes away.  Before incurring the expensive cost of shipping an amp to/from Canada, be sure to speak with their technical customer service.  Also, the AudiogoN discussion archives has a wealth of information.  Type in 'ground loop'.  This is no different than a car mechanic trying to figure out why your car is stalling. It could be any number of things. Good luck!