Tony, Can you say what "tube gear" would be more affected by humidity than SS gear? I don't think so.
The symptoms Henry describes do not at all sound like anything that can be caused by poor grounding. RF, maybe. Henry, what did your PS Audio do when the wall voltage varied up and down? Did you notice any change in sound quality? If it happens again, you may try momentarily bypassing your PS Audio, in order to determine whether AC voltage instability might in fact be causative. If you are close to a power station, there may be very high voltage lines somewhere near your house; those can certainly radiate RF garbage.
The symptoms Henry describes do not at all sound like anything that can be caused by poor grounding. RF, maybe. Henry, what did your PS Audio do when the wall voltage varied up and down? Did you notice any change in sound quality? If it happens again, you may try momentarily bypassing your PS Audio, in order to determine whether AC voltage instability might in fact be causative. If you are close to a power station, there may be very high voltage lines somewhere near your house; those can certainly radiate RF garbage.