Relationship of amplifier sound to transformer quality?

If the transformer is not wrapped with low frequency high permeability mu metal sound quality will suffer. No two ways about it. The toxic effects of the induced magnetic field extends to everything within what, about a foot of the transformer? At least.

"Magnetic field outside of toroidal transformer is theoretically zero. It is completely contained inside of the core. Toroidal transformer has no gaps making it more sensitive to presence of DC voltage."

Theory doesn’t seem to hold for a lot of things in audio. I wrapped a toroidal transformer, the aftermarket transformer in my uber modded Oppo 103, and heard good results. Maybe it doesn’t take much leakage to be audible, who knows?

"if the transformer is hand wounded using high quality silver wires with iron-nickel alloy in Double-C configuration, will this give deep bass without compromising the highs and still sound quick & agile?"

I imagine that combination of metals would work rather well since, you know, iron-nickel alloy is mu metal. I suspect it would sound like a million dollars.