I have decided to "split the baby" by using dedicated lines for everything and installing a low resistance chemical ground, but without system-wide isolation transformer/balanced AC, and then using a Torus isolation transformer/balanced AC device for only the turntable and phono preamp.
This set-up forfeits the single point of ground benefit of a wall-mounted isolation transformer/balanced power device which powers every component, but assures that the amplifiers will not be current-limited by too long a power cable run to a wall-mounted transformer, yet will provide the benefits of an isolation transformer and balanced power to the sensitive, low-signal-level front-end.
the problem with this approach is noise in your amplifier. 'street' power grid performance is not predictable. do you feel lucky today?
i have balanced power outlets from my Equi=tech 10WQ isolation transformer, sitting next to my direct outlets from my standard (non-isolated) power grid.
game, set, match to the balanced, isolated power outlets both for my amplifiers, and sources. it's smacks you right in the nose with the difference including better dynamics. power supplies perform better with cleaner power more consistent.
and I'm out in the mountains, away from any industry, in a newer housing development, supplied by hydro-power, with my own dedicated transformer just for my home at the street. so the local infrastructure is ideal. yet the delta of advantage is great.
you will never know what you will be missing until you actually compare one approach side by side with another.
as far as a dedicated transformer for each line that is not real world. lots of little baby/toy transformers/conditioners will more than likely add noise.
get a big boy transformer.
what you need is a large enough transformer to have proper head room for amplifiers.....ideally a transformer size about double of what you calculate as the max you need, but then filters at the wall panel (to prevent back flow of noise) on the circuits/outlets that are involved with digital. i have 3 filtered circuits/outlets; one for my digital front end, and one each for the class D subwoofer amps in my bass towers.
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