Anyone listen to Zu Audio's Definition Mk3?

Spirit,
First off, congratulations on your new Def 4's. I'm sure you'll get them dialed in.
I finally got mine dialed in after many weeks and many hours of tweaking, moving them around, rolling tubes and a new amp. These took a lot of work to get right!
My final positioning is 12' apart with only 5-6 degree toe in, 1' off the rear wall and I'm sitting 12' back from the speakers. Sounds glorious! Vinyl, CD or anything I feed it.
I will mention that when Sean was here (back when I had my Def 3's) I had my speakers about 8' apart, and the first thing he said was "spread them out more". I did, and he was right.
Curious, do you listen to CD's and then vinyl in the same listening session? When I did this, vinyl never sounded as good as CD. And vice versa as well. Now I have all vinyl or all digital listening session.

Sean set up my Def 4s. They are on the long wall, about 11-12 feet apart, angled in about 30 degrees, and within only a couple of inches from the back wall. One of my goals was to optimize off-axis listening, maximize the way that the speakers project the music, etc. - since I do not have a center listening position.

Hi Markpao, you certainly haven't understated the situation when it comes to the need for constant tweaking of the 4s to get them to sound of their best! I'm back to less toe in, but 8' apart is as far as I'm likely to get.
One big difference which has helped, is to drop the Low Pass Filter setting on the sub bass from factory preset 60 to 40 (initially I had turned it up to 90), and volume to maximum. This has reduced absolute quantity of bass but seems to have improved it's overall clarity and extension. In my room this seems to be working now the sub bass only really comes in at the gentle roll off point from the FRDs.
I'm a little confused by the PEQ Gain, PEQ Frequency and Phase sub controls. In my room at any rate I can't discern any change to sound quality with any variation in these settings.

On the Zu vs Coincident questions... I own a pair of Zu Essences. I have not heard the Coincidents, but my guess is that the Coincidents will throw a deeper soundstage, front to back, while the Zu's will be a bit quicker on the attack. I am guessing that the coincidents, with their narrow baffle MTM, have great midrange dispersion. The Zu's have a wide soundstage but it is not remarkably deep. I can't vouch for tonal differences, but I can say that the Zu's are stunningly sweet and detailed with the right equipment.

Severe toe-in for Def4 doesn't make sense to me and is the exact opposite of my experience with them although for those placing speakers 12' apart or more, I can see more toe-in than I use may be necessary. My Def4s are placed 9' apart, center to center, and one of the clear improvements of the Zu nano FRD even if mounted in Def2 or Druid is the broader horizontal dispersion compared to older Zu drivers. So I hear less toe-in is needed for proper sound staging than for earlier Definitions. I also cannot replicate any similar experience where different speaker positioning is needed for 16/44 digital vs. vinyl analog sources.

Spirit, the toe-in and positioning 4' out into the room, with the imaginary Crosspoint being 4' in front of you is reminiscent of the setup advised by Audio Physic for the initial version of the Virgo in the 90s. It was quite effective with that speaker and in fact the speaker wasn't well placed conventionally, if you cared about soundstage. But that speaker bears little behavioral similarity to Definition 4, so I don't have any correlating experience that suggests your setup should be optimal, nor that you should have big differences spatially between analog and digital.

Sean & I (I was volunteering to help Sean get back on the road fast) set up a pair of Def3s for a Zu customer in Los Angeles a few days ago. One thing that was handy was having two people to move speakers while the listener evaluated placements. In his room, there was very little latitude for spacing the speakers apart so he ended up about 9' on centers. We started with mild toe-in to get our bearings and then with the listener in the sweet position, Sean and I incrementally rotated toe-in around the front inside corner point until the owner's preferences for sound staging snapped in. He's not an inexperienced listener. You have a continuum of spatial options from extreme focus to expansive staging, and anything in between. No toe, and the middle of the soundstage starts to tear. Too much toe and the acoustic space collapses (though focus might remain). Since there is no way to be sure how most rock, blues and jazz recordings reference an intended sound image, this is an area highly subject to preference as well as to the variances in how individuals perceive acoustic space and spatial cues. We ended up simply dialing toe-in to his preference and it was pretty much spot on where Def4 toe-in works in four rooms I have listened to them in so far, here in LA.

Then at Sean's suggestion we dialed in some rake, deviating to a little back-lean from level. in some respects rake angle variance was more influential to image precision and tonal balance than toe-in. The adjustments have to be quite small too, by increments. It sounds tedious but the owner was seeking a trifle more vocal presence, and a slight tilt back nailed it for him, in his room.

Most people live in rooms presenting some acoustic anomalies, so I can't rule out that I might agree with your severe toe-in, Spirit, if I was there to hear it. But my experience with Def4 in a variety of rooms doesn't correspond with what you're suggesting.

Phil