Isolation transformer question

The only time I had intrusive hum on the Plitron within my BPT was when I had an over voltage situation with my provider, 125-126V. I also had noisy power trans. in my Art Audio 845 and Coincident 845 amps, I ended up building bucking trans. to quiet those (no amps ever on PC for me).

I also have experience with battery vs AC powered equipment, had Nirvana Electronic Works SS class A amp which ran off 4 wheelchair 12v batteries, Merlin speakers back in the day run a BAM (essentially a preamp, rechargeable batteries), and experimented with battery vs AC power for preamps, dacs. I'd posit if going battery, Stromtank level of design and build quality  may be necessary.

Large capacity transformer in PC and only run front end equipment off PC, no issue with saturation. No doubt grounding is an issue, I completely redid grounding in my house, no more ground loops with potential issues resolved.

@lewm pointed out the difference between these types of PC, this is consequential.

@atmasphere , what are your thoughts on balanced power isolation transformers?  

@testpilot I'm skeptical there's any benefit if the equipment you're using has a competent grounding scheme. You always have the issue of pushing any isolation transformer past 50% of its rating- that does not change with balanced power.

A good balanced transformer will have an electrostatic shield which any good regular isolation transformer will too; electrostatic shielding is a really good thing- it prevents capacitive coupling between the primary and secondary windings, which in turn vastly reduces high frequency noise from getting through. I'm curious if this might actually be a larger portion of the 'benefit' people perceive when they go to balanced power.

here is how a transformer works:

GI GO.