Help with Hum issues.

I realize you have done a lot of stuff to find your problem, never the less if you haven't already done this I would highly recommend it. The easiest way to source a hum is to disconnect all of your sources from your amp. Turn the amp on - any hum? If not, then connect your next source to the amp. Any hum? Etc.  When it starts to hum you have identified the source, now you can more easily solve your problem. The problem could be in the source itself or in its connectivity (wires, wire distribution etc.)

OK. Did you try what I suggested?  What happened?  That always works for me when I'm trying to source a problem.

Following up on my post, your speakers should be connected when you start with my suggestion.

1) First connect ONLY the amp and speakers. Turn on. No hum then on to step 2)

2) Add pre-amp with no sources connected, such as your tuner, phono, etc, connected do the pre-amp. Turn on. No hum then add your sources, one at a time, starting with the tuner. You should find a hum in one of these sources. Just a WAG, but I suspect you have a tuner with a bummer R channel.

Have you tried using a ’cheater’ plug on the end of the preamp power cord? Some times it is good to have only one plug with the ground (on the amp cord) - the rest of the stuff benefits from that ground. It is safe, if not preferable, to use the cheater plug on the pre-amp (if that works) until you can source the ground issue causing (if it is) your hum.

Although I don’t think your problem is the power strip, to rule out one more possibility, you might plug them into separate outlets and see what happens. Another thing to consider is the placement of power cords and IC’s. If you can, be sure that they are not close to each other and if they must cross do so as close to crossing at a right angle.

And if you have used the same IC’s with all of your stuff make sure you have IC’s which are properly constructed to reject EMI. I had a right channel hum once that was the result of one IC passing too close to a transformer. (I recently saw a diagram of a Canary IC, LV-77s on Blue Jeans site which shows a high quality insulation/reject of EMI which is used in their own audio cables)

FWIW, there is no easy fix for your problem, I think. Since you have used different amps and preamps with identical results its got to be some where in the electronics preceding the preamp.  

IC’s (short for interconnects) are what you refer to as ’wires’. There are low quality ones (thin, uninsulated, and cheap - usually furnished with inexpensive audio/vidio components) and much better quality and insulated ones. This could easily be your problem (or not). I really have nothing further to offer you at this time except for kind wishes.

Good luck