Does this make any sense to you? It isn't an attempt to sell anything, in fact I think he said a power line conditioner didn't affect it.
http://www.decware.com/paper03.htm
I can agree with late night listening being special, at least here, but I attributed it to workday being done and isolation from cares, distractions and daylight.
The mains harmonics thing sounds like so many angels dancing on the head of a pin to me.
Clark in Peoria