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
Witchcraft
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.