Using a shore power isolation transformer at home?

Thanks, that was very detailed!

I am planning to install a dedicated line, and I am comparing the possibilities. Right now I have two main issues with power:
(1) sometimes the power transformer of my amp hums much louder than it should, and some "fraction" of this noise even penetrates into the speakers;
(2) the AC voltage can be anything from 118 to 124.

The former I hope to cure with a dedicated line (probably w/o any isolated transformer to start with).

The latter (which probably does not affect the sounding too much, but drives me crazy when I want to set the optimal regime for the tubes in my amp) I plan to cure with Monster's AVS 2000 variac+servo (I am almost ashamed to use anything from those bastards, but it looks like these servo-stabilizers are their only product that does what it says and is priced adequately, if buying used).

To have a layer of protection just in case AVS 2000 goes crazy, I plan to put PS Audio's Duet between it and my tube amp.

Does this all make any sense?

Except for the dedicated lines, not really.

Why not?

Voltage is unstable, and I want 120V sharp. Isn't a servo stabilizer the way to do that in a non-limiting, neutral fashion?

Just looked at this diagram from Monsters of their AVS 2000.

Probably, I will through away all pre-transformer filters, to make it even less intrusive.