I heard a demonstration of a Nordost grounding box at a dealership. The room had several dedicated power runs for a dedicated subpanel, and in terms of audible noise when no music was playing, there was none. Yet, with the grounding in operation it was easy to hear an improvement in soundstaging—solo singer and instruments seem to be floating apart from each other, and the sound was a bit less artificially edgy. It was a worthwhile improvement in a high end system. I would rate it a bigger improvement than power conditioning.
Grounding Box Q
I watched a rather long video by Calvin Gabriel from Shunyata talking about his grounding boxes. Let me just say that, based on the large number of people buying these and other expensive grounding devices, I believe that they must do something positive, but here’s what I don’t understand. If only a ground wire is plugged into the box, how can any current flow into the box? I thought you need both positive and negative. Or is it something like the ground wire on a turntable, where you just hook up a ground wire and it kills the hum?