Are these Speakers the BEST on Planet Earth ?...

I have actually heard them both with and without the BXT. They are better with but the price goes up a LOT.

I don't think they are the best on Earth but they are very, very good. I remember thinking that I might be able to save up for them without the BXT. You get almost a whole system. Just connect a streamer and you are good to go. It is like a combo of a speaker and an integrated with a built in dac. I will probably never buy them but hope equally good models will appear for a lower price.

Regarding D&D 8 they don't have anything like the BXT bass module. They might be a bit warmer.

The best I've heard was some large Focal Utopias and Magico M6.

"Acoustics delivers 55% of S.Q."

I don't know where that figure came from or whether it's accurate, but I do know the geometry of the listening room is absolutely critical from at least 500Hz on down.  To that end the Kii speakers are pretty special.  The ability to process not only EQ but phase information in order to control dispersion at low frequencies allows them to accommodate the quirks of different listening rooms better than almost any other speaker.  Dutch&Dutch use similar technology to do the same thing, but I'm not aware of many others who are taking advantage of new DSP technology to alter they way sounds emanate from an enclosure *after* that sound has left the box.  If the Kii Three are the "best in the world" it's because they are employing brand new technology.  The same technology will undoubtedly be improved upon by other manufacturers in the near future.  I wouldn't spend that much money on something that will invariably be dated by the time the credit card bill is paid down.   I do enjoy seeing people write about how ugly they are, as though visual aesthetics are somehow universal or matter to the performance of a speaker.  Give me spartan, utilitarian gear that is designed to perform.  Money and effort spent on making audio gear pretty is money spent to appeal to senses other than hearing.  Pretty speakers appeal to the optophile.  There's nothing wrong with wanting something pretty, but visual aesthetics don't play a role in how something actually sounds. 

@atmasphere -   Yep, E2’s low note on my guitars.     Standard Bass guitar goes an octave lower.    Conflation (touche')!

Hm. Sounds like you have a baritone guitar. That has low E at 82Hz.

FWIW the SVT amplifier was designed around hifi ideals (by Roger Cox who retired from his position as VP at Fender a few years ago), at least that's how he put it to me.

And here I thought I was doing at least one thing, in my life, that was, "normal".      ie: https://www.quora.com/What-are-guitar-string-frequencies                 Whatever Mr Cox’s goal; he hit it out of the park, with the SVT.