Air Tight ATM-2 mechanical hum.

My new Air Tight ATM-2 emits an audible hum (which can be heard from 3-4ft away, music off) from its power transformer. Although the output at the speaker is fine, i'm curious if this indicates any defect (cuz i expect a dead quiet unit in this $9,000+ price range). Anyone has any input? I'd appreciate your contribution.
Thank you.
The transformer on my old ATM-1 was quiet, for what it's worth. Hum that audible seems like a defect. You may want to contact Tom Tutay in Florida, he's the East Coast service center for Air Tight and a really good guy. If you Google his name it should give you contact info. Good luck!
Thanx Jond...I talked to the dealer and he said some transformers are more susceptible to minor voltage differences (117VAC, 120VAC) of the power outlet (or the quality of the power) in differentt areas..hence they can be quiet in some systems and buzz in some other. The thing is my neighborhood is pretty new (2, 3 yrs old) so i dont think the powerline here is that bad. I did ask for an exchange (I only had the Air Tight home for one night) ..he gladly agrees but i have to wait for 4-6weeks :( Hopefully the new one is ok . Wish me luck !
FWIW my ATM-2 is basically silent, though you can hear a slight hum from the power transformer if you put your ear right next to it (careful around the KT88s). If you're on the West Coast and once you're beyond the warranty I would recommend Nick Gowen at True Sound in Campbell, CA. I had a series of issues with my ATM-2 resulting from "improvements" implemented by the previous owner. Though expensive Nick made all right again.

Enjoy - this is one of the best amps I've ever owned.