Anyone listen to Zu Audio's Definition Mk3?

I can't thank everybody enough who has taken time to contribute to this part of the thread. What I'm finding with my Zu-Hovland combination is a great synergy, but the 4s are so revealing that I believe I'm hearing the sonic fingerprint of my Radia SS power amp as a slight steeliness/edginess where the leading edge of notes is at the expense of the full bloom of notes. It's just a hint, but I suspect that all tubes will take me in a better direction. In all other respects I love the combination. Interestingly my cd player sounds better than ever, but I can really "hear" the mechanical nature in digital clearly not present in analogue reproduction.
It's getting harder and harder to audition all types of equipment, esp. if like me you don't have a relationship with a single dealer.
So I'm going to spend plenty of time (and perhaps not a little cash) investigating SET 845 v OTL, in the form of Audion Black Shadow v Atma Sphere/Dave Berning. Luckily all three brands have good representation in the UK, and all three have the thumbs up from those who've heard them with the 4s (Phil re Audion, UK Zu distributor Simon Matanle re Atma Sphere, and Roy Gregory who reviewed the 4s for Audio Beat re Berning).
A lot of other repected choices don't have UK distribution, so it's down to these three.
Loathe to replace my Hovland HP200 tube pre, this I really do believe to be liquid and revealing, and has benefit of remote control.
I'm really craving even handedness and neutrality, so I want to make certain that any extra tonality that might be present in SET over OTL isn't a colouration taking me away from this goal.

Spirit,
Your decision to audition all three of these amplifiers is wise.You`ll get endless opinions from the rest of us based on our own experiences and personal taste. Only you have your unique pair of ears and this is the best way to choose what`s best for you.I`m sure builters of SET amplifiers(or any other amp topology) could make their case as passionately as Ralph naturally does for the merits of his OTLs.Listening will settle it for you.
I look forward to your exciting endeavor.
Regards,

+1 to the last comment. In a big way. At some point it is all about hearing something in your system and seeing how it meshes with your room, equipment and preferences. Let us know how it all turns out.

You reap as you sow Mr Anderson.

Did you ever have the Defs on Sistrum or just Equarack and Stillpoints?

A little info that may explain the assertion that the 4s with OTL sound possibly lean thru the midbass, and analytical with emphasised treble, versus SET 845 which may present more body and a richer tonality.
It seems that the capacitor, a Mundorf, on the high pass filter to the Radian tweeter would present a very hot treble thru the Radian 850 with OTL.
A solution to this would be the replacement of this capacitor taming the very top end a little to accommodate the OTL more successfully.
Apparently this is a rel simple job involving getting to the back of the tweeter, the capacitor is not even soldered, just a straight swap.
Interestingly on the 6Moons preview of the Druid V, the Italian distributor has done just this proceedure to alter it's high end character.