Slight hum in my amp. Is this normal?

***UPDATE***
My Anthem A5 will be here Friday but one caveat, just picked up my (new to me) Anthem P5 from UPS. OMG is it a BEAST! Holy crap, it's 130 lbs and just connected it up. This may not be the place for a review and I cannot articulate like the pros, just sharing my latest events. The Integra 50.3, my spare unit had to pacify me while the A5 was traveling from Los Angeles to Ontario Canada, it's birthplace. Sure it didn't sound anywhere as good as the A5 and as I yearned for it's return, fond this P5. Of all places, Craigslist. It came with 4 Audioquest Diamondback XLR cables. Why not 5 is a mystery. I'm not crazy about the Diamondbacks because they look like very early versions with choke type strain reliefs that clamp/screw together. In addition, a pair of Transparent Musicwave Super speaker cables, 12 ft length. These things are HUGE! Im curious to how they will sound compared to my Audioquest Type II speaker cables. I think I'll keep the Integra as a spare and put the A5 up for sale. I hate to since it's in near mint condition however, I'd say the P5 is a nice concession. Wouldn't you?

Just had my Levinson 23.5 serviced by an authorized Levinson repair center with many years of experience, capacitors were replaced not the big blue capacitors the medium smaller ones on the board 680UF 100V and other small transistors and resistors, there is no hum from the speakers at all, dead silent but when I opened the cover to look at the repair I place my ears on top of the amplifier I hear a slight hum you have to get really close to hear it. I assume it is normal maybe one day when I can afford a new amplifier I will have something to compare but I am happy with the Levinson 23.5 don't have any desire to replace except for a Levinson 33H.