Decision between Zu Definition OR VS DB99

These two are quite different designs. Some things to consider just by LOOKING at them:
VS:
The VS uses a 10" seas woof, commendably placed low down to get benefit fm floor boost and with a transmission line. There's a 7" mid in a tapered back chamber (I think? What's a "terminated" transmission line?), & a tweet with a wave-guide (both drivers of undisclosed origin). The mid has a quoted 100db sensitivity -- which is unusually high given the quoted motor specs; maybe this sens is using the internal amp. In any case it's excellent.
The bass is active and, again it seems, they use a high input buffer on the internal amp to power the mid as well (difficult to understand VS' techno-marketing). There is a passive xover, possibly a series (what on earth is the quoted "Global Axis" this xover is supposed to integrate? Phase?) and L pads to help tune some of the drivers.
The system's sensitivity isn't evident; what's quoted "in room" looks like ~90-92 anechoic.
Interestingly, given the "booster" amp, the system's impedance should be very benign (with reserve re, the techno-maktg). Excellent characteristic.
OTOH, does this mean that one has to go through that amp's circuitry before reaching the mid+woof?

The Zu uses two 10" woofs (sourced possibly fm Eminence, "US made"), active, covering apparently a single octave (~50-~25 Hz) with a line-level 24 (L/R?) filter. Then there are two wide-range units in a MTM config and an Audax tweet with a wave-guide.
The two wide-rangers cover most of the musical spectrum, so you have a quasi point-source that's driven full-range -- i.e. there's no added xover (is there a notch filter s/where in there?). The amp drives these more or less directly and full-range.
The Audax tweet kicks in full blast very commendably high up, ~15kHz with its 1st order filter @ 12kHz (excellent idea, nice 90 degrees phase angle, and you can do that with ONE component only).

Design wise, this is starting to "sound" real good: minimal (if any) phase, delay, amplitude & power anomalies, in the critical range ~100-~10kHz.
OTOH, 1) you get narrow horizontal dispersion as you go up (due to the 10"ers beaming) 2) how do they integrate TWO drivers to simulate a single point-source???

So, on paper, the Zu looks as lovely as the VS interesting. In theory, the Zu should offer very good transient attack, coherent and well-balanced sound. In theory it won't image exquisitely -- but well enough. It should also be relatively easy to place and drive.
The VS should offer a meaty, dynamic sound, and should be exceptionally easy to drive, and should image easily and very well.

All this fm looking -- now how 'bout s/one who's tasted the pudding (to coin a phrase)? Cheers

Gregm, your post is based upon speculation, not having heard the Zu Definitions (which you graciously admit). Unfortunately it contains some errors.

Nealhood, Zu offers a 60 day money back guarantee and in fact insists that you keep the speakers for that long so you give them a chance to break in. They sound great with tubes and are OTL friendly.

Gregm - Zu makes all their own drivers. Each cabinet contains 4 x 10 inch powered woofers in the rear. Each front sports two 10 inch mids and a super tweeter in the MTM arrangement you described. These present 101 db efficiency at 6 ohms. This is a nearly resistive load so it is very amplifier friendly.
Actual listening seems to support their claim of 16Hz on the bottom. I found imaging to be very good and depth of soundstage very convincing. I hope to be buying a pair of Definitions very soon. Meanwhile, I bought the Druids. These are much more cost effective than the Defs but with 5 fewer drivers per side, they don't quite do the same thing.

Essential, old sport, a most unfortunate misfortune in my post seems to have inopportuned you. Which, pray, are the erroneous points? The mistakes (as opposed to the errors)?

BTW, if you own (or have used) Zus, can you give a quick summary of actual sound characteristics?
Jokes apart, it's really a very intriguing design.
(BTW, don't want to be seen as bashing the VS -- I just happen to be interested in the Zu). Cheers

Thanks Macrojack. I had overlooked that there are 4x10" woofs per side (rather than 2). So much the better. I expected the imaging properties to be good - I just want to know if they present a pin-point/ "reductionist" image (which I doubt) or a more holographic type. Fm what you say, the latter seems to be the case.
Using two wide-range drivers is what intrigued me -- they cover a very large range downwards and I wonder how they dealt with intermodulation and coupling the two.

BTW, looking at the Druids I can understand your interest in the bigger model. BTW, the yr spkrs have a different tweet and a heftier hi-pass filter than the Definitions.
Cheers