Slight hum in my amp. Is this normal?

***UPDATE***
Well, my Anthem A5 made it to its birthplace safely and today I had a conversation with one of the customer service reps. Sure enough, there WAS a problem. Replace a couple bad capacitors. I don't have the hard copy report yet but I'm glad they DID find a problem, confirming I wasn't imagining the "buzz", "hum", or whatever!
As soon as I get the full report, I will list the problems here.
Also, I located an Anthem P5 for a killer price that will be replacing this A5 so it will be going up for sale if the P5 checks out healthy upon arrival. STAY TUNED !.......

Sounds encouraging! Think I'll roll the dice and see if Prima Luna can fix the hum in my unit.

Just received the service report. All of the power supply capacitors (they look like long C-cell size batteries) needed replacing. It's like a new amplifier now. I understand the caps are what fails soonest in most cases. Funny thing, I just purchased an Anthem P5 that will probably replace this A5 and if so, will be up for sale....