Using a shore power isolation transformer at home?

Ngjockey, thanks!

Can you please clarify what do you exactly mean by "grounded input"? Shortening the neutral THAT COMES FROM THE PANEL TO THE TRANSFORMER to ground? Why is that a good idea? I've never heard of doing that (I am not very experienced with "pre-receptacle" wiring and might be wrong here: when you take something right from the panel, you can, probably, assume that ground and neutral are, essentially, the same).

Let me ask two more questions:
First, is it a better idea to have 2:1 transformer, converting 240 to 120?
Second, is it a good idea to add "enhanced grounding" via some buried rod?

Thanks!

Just attach both grounds together with the shield wire, if it has one. In the case where primary and secondary are on opposite sides of a transformer, both grounds screw down to the casing on either side. If it's metal encapsulated, that should be attached to ground as well. Continuous ground.

Ground and neutral are not, technically, the same. That's why they are different wires.

1) If you're using a 480/240-240/120 step-down transformer, such as the encapsulated Acme or Hevi-Duty, you must use 240V in. Cheap on Ebay - industrial recyclers. Can be more expensive for shipping.

Topaz/ Xentech/ Phoenix are available in 240/120 and 120/120V models. The former can be used with either voltage in. Surplus distributors, Ebay occasionally. More expensive than general purpose, industrial step-downs.

If you have dedicated circuits and you're hard wiring, 240V has some minor advantages. However, minimum code in many areas for 240V wiring is 12/3 with a 20A rating (12 gauge, 2 insulated hot, 1 insulated neutral, 1 naked ground which is not counted as a conductor. That's even if the neutral isn't utilized). If you're splitting that up before the transformer, that can lead to phase issues. If you already have dedicated lines, chances are they're 12/2 and not suitable for 240V. Locating the transformer near the distribution panel solves that issue as well as mechanical hum, if the panel is in an unoccupied area.

For either type, the maximum draw (aside from momentary start-up spikes) must not exceed 80% of the transformer rating. For audio, I prefer closer to 50%.

2) Usually a bad idea. Been discussed a few times on these forums. Even if they're bonded together, which is a must, there might be issues if they are not in close proximity. An additional ground rod for assurance, within a foot away from the original, should be fine, if you know what else is buried there. Of course, I'm just guessing. I'm not an electrician but I stayed at a Holiday Inn last night.

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?