You don't mention if the hum is from the speakers or the amp. I had one of these on loan and the amp itself gave off a hum, not a transformer hum, but sort of like a hum from the tubes resonating (?), that could be heard from the listening position during quiet passages, after the amp had warmed up. Didn't try to solve the problem, just returned the amp.
Tube Amp Hum
I have a Golden Tube SE100 that seems to have alot of hum or buzz. I can hear it on quiet passages.I have a pair of VMPS Super Towers that are very efficient. Any solutions? Rich