I saw this years ago at Guitar Center. A dingus that sits between your gear and your power to take away noise. In the store, they had it on a thing with a neon sign, showing that the noise that the neon sign generated would not come through your gear.
I am sure this is it. The Hum X from Ebtech, which seems to be a part of Morley.
The Hum Xtm filters out unwanted voltage on the ground line that can cause ground loop hum.Elsewhere, it says "Not A Ground Lift", but it seems to serve that function, but in a safe way.
Here's the thing. The place where I'm most likely to put it, it's on a power strip where I plug power adapters to a device that takes DC power, my ToneWorks AX1500G multi-effects unit, and if that has no ground plug, like most DC power supplies, then how can it experience ground problems? Will this thing even help me?