I have been following this thread and feel its time to post, seeing you have now called George a troll for the second time.
George has nothing to gain from these posts, as he does not build amps or speakers, AS YOU DO! He has presented nothing but facts, and left out statements of linked reviews you presented.
And as for my own experience with the Zero Autotransformer, Ive tried them many times, and on a matched amp/speaker combos, they are a big step backward in sound quality IMO. They are as George puts it a band-aid fix, for people who have a mismatched amp/speaker combo that cannot be driven correctly - yet have no desire to change either to correct the mismatch and fix the underlying problem.
Sure, they can live with what they have using the Zero, but that will introduce another set of problems that then affect the sound quality. Is it worth $1140 for a band-aid fix??????? Or should they fix the mismatch problem, THAT is the real question????