On one leg or two legs?

Hevac1,
It couldn't hurt if Maril555 moved the projector branch circuit over on the other leg, L2, of the sub panel. Might even help in balancing out his main electrical panel.
Will that solve his hum problem? No, jmho.

As for the total load that is connected to L1 leg of the sub panel, I would just about bet the total combined FLA of all the associated audio equipment is 20 amps or less.....

Even when just a power amps connected to the speakers, and nothing else connected to the amps, and with grounds lifted on both amps with a cheater plugs, still I hear faint hum (much louder with no cheater plugs).
I have tried everything:
Unplugged every piece of equipment, and turned off all circuit breakers,
Lifted grounds on every single piece,
01-29-09: Maril555

Maril555,
If your hum problem exists with nothing connected to the inputs of the power amps to the extent you even used ground cheaters on the plugs of the power cords maybe the problem is the power amps and the The Bolero's sensitivity of 92dB/W/m.

(much louder with no cheater plugs).

Again with no ics connected to the amps inputs?
Just the amps connected to the speakers?
Totally isolated from one another?

OK....before you kill yourself and us....pull out your amp and take it to an audio store...or high end used equipment seller....or just a friends house who has some halfway decent speaker (almost anything costing over $100 will do).

Connect the amp with no input to their speaker(s). See if there is a hum and if it changes when you touch the amp case. If it does....fix your home electrical so it's up to code and get your amp fixed.

If there is no hum...come back and we'll work on the problem.

Jea 48,
Just last night I did another experiment- connected both power amps and preamp to a single outlet with a power strip, no cheater plugs- faint hum in the R channel and louder hum in the left.
Funny thing is, that I have the same model power amp before, just in stereo configuration (BAT-75 SE), and had the SAME problem, hum louder in the L channel.
I am absolutely sure the amps are fine, they are on loan from my friend, and are absolutely quiet in his system.
I didn't take them to my living room system to try, just because they are so heavy.
I will try again with no ICs connected, but then I'd have to use plugs in the inputs, otherwise they pick- up noise as antennas.
Ghstudio,
I'm pretty sure my electrical is up to code, as Jea48 seems to agree with.

Just did it again- no ICs connected, plugs in the inputs- same hum.