Ground Cheater plug or....

Absolutely do not use cheater plugs. They defeat the ground that is there to protect you, your equipment, kids, wife, girl friend in the event of an electrical fault. Find and fix the electrical problem causing the need for a ground loop. Be it, bad interconnect cables, bad electronics, bad ground system in your home, however, you will find many people telling you to use cheaters. You are asking for trouble if you do this. No electrician in their right mind would tell you to defeat the home ground system by using cheater. It is relatively easy to find the cause of the problem, isolate it and fix or replace it.

if you have a hum or ground loop, I can tell you how to systematically find it, isolate it and what you can do to get rid of it. But do not use cheaters.

enjoy

The hum remains even if the ICs are disconnected from the amp.

Then the hum is most likely not being caused by a ground loop, and it most likely would not be fixed by either a cheater plug or by disconnecting the safety ground inside the outlet.

The reason I say "most likely" is that there is a SLIGHT possibility that the hum is being induced by two different means in the two situations. By a ground loop when the preamp is connected, and by pickup of emi (electromagnetic interference) when it is not. With nothing connected to the amp inputs the possibility of emi pickup is increased, because without the preamp being connected the impedance at the amp inputs corresponds to the high input impedance of the amp, rather than the much lower output impedance of the preamp.

My suspicion is that the amp itself is generating the hum. To confirm that, put shorting plugs on its inputs, and turn off or unplug everything else that is nearby, that could conceivably be a source of emi. If you don't have shorting plugs, and assuming the interconnects are unbalanced, connect them to the amp, leave their other ends unconnected, and WHILE THE AMP IS TURNED OFF stuff some aluminum foil into the unconnected ends to short the RCA center pin and ground sleeve together. Make sure that the foil is securely in place, so that it won't dislodge when you turn the amp on. Do not let anything or anyone touch the RCA plugs while the amp is on. And after assessing the hum level do not remove the foil until a minute or more after you have turned the amp off.

Also, this paper may be of interest.

Finally, as I see it creating a code violation inside of an electrical outlet, where it might be forgotten about in the future, severely compounds the already non-negligible risk that using a cheater would represent.

Regards,
-- Al

OMG Dopogue, I almost fell out of the chair laughing. They'll be shipping by next week and carried by Music Direct.

If you have cable or satelite hooked up on a dual use rig like many here unplug incoming signal wire to box and if hum is gone fix the earth ground, usually company will fix for free.

Just run a long extension ac cable from your amp to another outlet that you know is on a different circuit.This way you don't have to move your amp.