MEN 220 creating hiss

[KaliKid2013]

Hello,
About a month ago, I added a new men220 into my system.

Ever since I did so, it seems to be creating a slight hiss. So today I had the time to try to troubleshoot it, I did everything I could possibly think of, and it is still there, without the men220 my system is silent.

I have the outputs from the c500 preamp going in to the inputs on the men220, and I have the outputs on the men220 going to the inputs of my monoblocks.

I swapped out all of the XLR cables, and the power cable.

I added a 3-prong to 2 prong adapter when plugging it into the MPC 500 power controller.

I tried the low and high balanced outputs on the men220. The unit is correctly set to balanced outputs.

I unplugged the power cord from the MEN 220 going to the MPC 500 power controller, and plugged it directly into my dedicated 20 amp outlet, both with the three prong to 2 prong adapter, and without.

I changed the placement of the men220.

I turned off every single breaker in the house except the dedicated 20 amp circuit for my system, I turned off everything the refrigerator the stove everything in the house was turned off. So there was no other electronic devices running in the entire house except my system.

At this point I am out of ideas, I was going to call Chuck Hinton at McIntosh Monday, but figured I would see if anyone here with the men220, or any other Macintosh devices, maybe had a similar problem, and if and how it was resolved.

Thank you for any assistance.