Hello Tom,

What you are describing sounds like mechanical hum from the transformer which is usually caused by something external to the amp, it's rare to have a faulty transformer. It's something we never see with these amps.

Use a heavy extension cord to plug the amp into several different circuits throughout your home. You should eventually come across an outlet where it no longer hums. If the problem ceases to exist with another outlet then there is most likely too much current draw. A textbook symptom of inadequate power with an amp using a toriodal transformer is that it will hum from the chassis if there is a voltage sag. Sometimes it's not the voltage, it's DC offset voltage across the AC line. Unfortunately this is tough to pinpoint, the only way to verify whether it's the amp or environment is to physically move the amp to another location. Obviously this is the last course of troubleshooting but it's sometimes necessary. It's probably nothing to worry about and you should be able to pinpoint the problem using the extension cord tecnique. It could be something as simple as a halogen lamp on the same circuit. During troubleshooting try to think of anything sharing an outlet in that room however benign you may think it is, dimmer switches, heater, any appliance, etc. I should add that we've had a few amps sent in for mechanical hum and to the best of my knowledge none have exhibited hum in our test environment. Please be syre to contact me if you have any questions or need to troubleshoot further.

HELLO STEVE:

After using the above extension cord tecnique i found the hum went away.
So i think ill just add a seperate 20 amp circuit just for the amp .... it worked but only if thats
all that was connected into that Plug as soon as i add ANYTHING Else (EX:990) the Hum would return
so i just run it (AMP) without sharing the outlet .... so far so good

Now just the other day while listening to music (not that it matters but low volume) and working around the house my wife turns on the hair dryer in the bath room and slowly the sound disappears
and the HUM returns (turning the hair dryer off everything returns to noraml)

Is that AMP drawing that much current that i can't run it in MY HOUSE ??? (I really don't want to return it) but i'am a little confused about what i should do and what my options are

am i right to say that if the ONLY thing running in my home is the 990 and 7500 and CD player that i SHOULD not have any problems because there the only things using Current ?