On Wednesday I had an electrician in whom I have great confidence install two new dedicated 20-amp circuits for use with Perreaux mono blocks when I move them to a new location in my exercise-area system. Both circuits originate from the main panel for the house.
To test them, I plugged in the amp that I am now using in the exercise area. In each of the new circuits this produced a fairly loud hum from the amp.
At the same time, I also had the electrician install another new dedicated 20-amp circuit for use with a treadmill in the exercise area. This circuit uses a normal 20-amp GFCI receptacle, and unlike the PS Audio receptacles, it does not have an isolated ground.
When I tested the amp by plugging it into this new GFCI circuit, there was no hum. The is also no hum in the dedicated GFCI circuit I have been using for years for this amp in the exercise area. This circuit is wired into the same panel as the new circuits.
This suggests to me that something about the isolated-ground receptacles – the PS Audio ones – causes this hum, and as a test, I am thinking about replacing one of the PS Audio receptacles with a standard 20-amp GFCI receptacle to see whether this eliminates the hum.
However, before I do this, I would appreciate any thoughts others might have about this problem. The two new circuits are unusable for audio equipment in their present state.