I am an easily confused old man.
My Atma-Sphere MA-1 140 watt tube amps use 5 amp fuses.
When I look at these fuses, the wire connecting one end to the other is absolutely tiny. At my age I need reading glasses to see it. Yes it is that thin.
This is the conduit through which the electricity flows. All the electricity.
The question I have: do you have an isolated ground with this dedicated 20amp service?.
This involves running a new wire outside, connected to a new copper rod, and having that rod driven into the ground, deep.