Dear Mark58,
I intend to pair up the Torii MK4 with a pair of Zu Soul Superflys (16 Ohms).
Nope, I have not heard this actual combination per se (i.e. with the Torii MK3).
What I have read from the Zu website is that these speakers were designed to be paired with tube amps, i.e. the traditional low power and high Ohm type. So in theory, it should work. I'm keeping my fingers crossed.

I am simply relying on the GOOD reputation of both Zu and Decware.
Will post impressions a couple of months from now when both the amp and the new speakers arrive.
As for what made me finally pull the trigger on the Torii MK4?
Some months ago, I was ready to purchase the MK3.
That is because I came across numerous posts from owners of the MK3 stating that the sonics bested anything they have heard before, and those are $$$$ rich audiophiles who play with uber expensive low power WE300B SET amps.
Now given what a progressive company Decware is, I knew that it was a matter of time before the MK4 model would turn up.
I sure that an MK5 ... 6 and so on will eventually be produced.
But in the meantime, I trust Steve / Decware's audiophile ear.
So anything that sounds as good or even better than an MK3 is a no-brainer, i.e. "must buy" audiophile item for me.