Amp Hum

I've got a B&K AV5000 Series II amp with a hum. It gradually builds up over about a 5 second period on startup. I've disconnected everything (preamp, speaker cables) and still the hum persists. I tried a different power cord (Shunyata Sidewinder), made sure everything else was off, tried a cheater plug, different wall socket... still have the hum. I tried the Monidal Magic thing for the cable, still the hum torments me. Is it time to take it in or am I missing something? Thanks-
Is the factory cord actually grounded i.e. a three pin connector ? If it isn't, you might have the polarity reversed on the plug or the outlet. This can introduce a hum into the amp which is then fed through the speakers. Sean
If everything is disconnected and you hear a hum from this unit, I beleive you may have a transformer hum. (a noisy transformer) In this case, it would be wise to discuss this with the amplifier manufacturer. cordially, Richard..
Can you hear the hum from the listening position or when you put your ear to the unit. If the latter is true this is normal. Steve
Definately call B&K they are more than happy to advise you on potential problems or even suggest a fix. They are only in NY and a pleasure to deal with. A hum that is isolated to the component can be two things... faulty ground or
bad or noisy transformer or power supply...
take the piece over a friends and plug it in... see what happens and if hum still persists.. call B&K.
Good Luck!