Loud hum from left and right when passing ht signal through

I put this up on Hoffman's site as well.  I appreciate anyone who can help.  Below are details of my situation and what I have done so far to trouble shoot.  I'm thinking of calling an Exorcist.

This is a question for all of you electrical engineers out there.

In order to better my 2 channel sound (it worked), I bought a Schiit Saga +, connected the left and right outputs to my power amp and the left and right pre-outs from my AV receiver got connected to the first inputs on the preamp. All 2 channel sources were connected to the pre, and the multi channel sources stayed connected to the receiver.

For two channel listening, everything is beyond my expectations.

The tech at Schiit said that when watching movies, I should switch to passive mode on the pre, select the input that the pre-outs are connected to andturn up the volume all the way. When I do this, I get a low hum that sounds like a 60hz hum.

I tried:
Removing the tube
Disconnecting all sources except the pass through
Changing cables
Animal sacrifice
Changing outlets
Disconnecting everything from the receiver
Thoughts and prayers
Unscrewing coax from cable box
Unplugging everything, except what is being used
Turning off all lights, Air conditioner, etc
Killing power to the furnace
Unplugged and disconnected subwoofer

The power amp is a three channel that powers the front 3 on the receiver.

The only thing peculiar that happened during my troubleshooting was that when I unplugged the receiver the front left and right channels that pass through stopped buzzing, but the center channelstarted to buzz! That may be a clue.

The tech at Schiit has no idea what is causing this.

Thanks in advance.
Hook the the receiver directly to the amp bypassing the ---- all together. Hum still there?
Thanks.  That is how it has been hooked up for a while and no hum.  I just introduced the preamp.  Prior to last week, I was using the pre in the receiver with no issues.  The Schiit pre sounds so much better for 2 channel, but I can't keep it if it is going to hum like this.
Problem solved!
I forgot that I work with tens of thousands of the brightest engineers on the planet.
A friend from work said, "you gotta lift the ground". I then plugged the 3 prong plug into a 3 to two adapter, lifting the ground, and the thing is dead quiet!
You may have a ground loop. If possible, try plugging the receiver and pre-amp into the same electrical out. If you happen to have a power strip, power filter, etc., with multiple A/C sockets, try plugging everything into it so everything is on the same circuit. If the hum goes away, you can start investigating why you have a ground loop.

Don't lift the ground on AC devices!!

Try disconnecting your Cable TV input first, if that is the issue, get a cable TV isolator.
I tried the things above, but to no avail.  Now that I know that the 3 to 2 prong adaptor works, I will buy a ground loop isolator.