Eleven Rack Output to Amp buzz

[KarlDB]

Okay, this is totally weird.

I ordered a new RF/EMI filter and installed it, and it was no change. Noise still there. Then in the process of ruling out other things, I happened to unplug the Eleven Rack from AC power altogether and the noise is still there.

If I just have the 1/4 inch guitar cable plugged into the input of the Bugera, no noise, unless I grab the tip with my hand, which is normal. But, as soon as I plug that guitar cable into the OUTPUT to AMP jack on the (unplugged from AC power) Eleven Rack, the noise is back.

I don't know if the Eleven Rack is generating the noise somehow, or if it is just acting as an antenna and picking up RF or EMI noise somehow. I do have LED lightbulbs in the studio, and if I turn the lights off the noise gets slightly quieter, but it is still there.

Not sure what to think at this point.