Anyone listen to Zu Audio's Definition Mk3?

Agree with Glory, 213Cobra, you're a Godsend in setting down really detailed info that gets to the heart of the technical, and, more important, subjective experience of the Def4 experience over and above the Def2s.
Until this point I've really been happy to stay with my Def2s, but only since I've added the SpatialComputer Black Hole bass attenuator to sort out room nodes/standing waves, which has helped the 2s to integrate thru the low end I didn't think was possible. Sean Casey at Zu helped put me in this direction. I'd really recommend all Zu owners (and others) to investigate it, I believe Sean demoed it at Def4 launch at RMAF 2011, and I'm sure the 4s will benefit also.
My main push twds the 4s has been helped by comments that the Radian supertweeter really has helped the top end, that certainly lagged behind the FRD's in the 2s and always drew attention to itself.
So 213Cobra, you really feel the high end is more complete, and of a whole with the rest of the spkr?
Btw, which finishes have all you Def4 devotees ordered your spkrs in?
Much as I love the custom black finish, I feel this may be impractical wrt light reflections esp. while watching movies, and day to day maintenance. My decision will rest between true black matte and Cosmic Carbon.

I love my piano black. Actually, I rather like the light reflections in the daytime and don't use them for video. Maintenance has not been a problem.

213Cobra, you mentioned tube based power amps up to c.30W/ch would suit the Def4s. I'm currently running a Hovland tube HP 200 preamp with a Hovland 125W/ch poweramp into my Def2s, which sounds sublime.
Even on a loud listening session I v.rarely go past half way on the preamp volume, and at night normally a little lower. Would I get more performance out of the Def4s (and pow amp) if I go to a lower powered amp in the 30W/ch region, maybe allowing vol to increase well past halfway on the preamp?
I have been v.happy with the Hovland combination, but am v.intrigued by DAVID BERNING tube based pre and pow amps which use V-OTL technology to eliminate transformers on the input AND output stages leading to a sound which has the best attributes of tube and SS.
I think this may be a match in heaven for the Def4s.
Comments?

The Hovland combination is excellent by any measure. As I've written before, despite the high efficiency, Zu speakers, especially Definitions, make good use of moderate to high power. The main issue to consider is that at 125w/ch, you are running a push-pull tube amp. There's a subtle grunge in the push-pull crossover signal handoff that is absent in SET, and which isn't especially noticeable until you experience its absence. An even excellent push-pull tube amp sounds slightly blurred and congested to me, after years of listening to big-glass SET. On the other hand, push-pull tube amps usually have better bass control and sound (and measure as) more strictly linear, all other things being executed to an equal standard. What is surprising to many who hear it for the first time, is how an 845 SET amp rated for 25w can sound equally or sometimes more dynamic than a 100+w push-pull tube amplifier, on a bursty, revealing and efficient speaker like Definitions.

You have to experience at length SET amplification to understand how it fits your perception of convincing musical sound. A Zu speaker is the perfect speaker to explore this with, and there is perfect concept continuity in mating a single-ended tube amp with a crossoverless loudspeaker. Just don't do it with an old-school slow and sweet kind of SET. At the expense level you're already playing, you can afford a good, objective SET choice. There's no reason you can't mate your excellent Hovland preamp to a good SET amplifier, so no need to take depreciation loss on two pieces if you decide to try the SET power amp route.

The Berning OTL option is also highly credible musically and convincing. Going transformerless but retaining the push-pull topology gives you some of the immediacy of SET but not quite the same thing. Berning has a truly clever OTL circuit that uses an RF carrier signal through a high frequency transofrmer to handle impedance matching without the audio-compromizing effects of an audio frequency transformer. The Berning gear, including the ZOTL preamp, have a specific brand sonic character, which is fast, dynamic and highly transparent. Some people hear it as accurate, others as a little sterile and lacking full tonal body. It's undeniably good. But so is your preamp mated to a suitable SET amp, which if selected well will give you a more holistic, toneful presentation with lots of body. It costs more to get the speed and sheer openness of the Berning in an SET design that delivers the full holistic sound that topology is capable of. Choices.

I think in many respects, the Berning sound can also be closely acquired in solid state in the form of Lavardin.

Phil

My Definition 4s are painted in a high-gloss 2011/12 Cadillac color, Opulent Blue Metallic, with the exposed aluminum parts natural. My Druids are gloss Ferrari red. My first Definition 1.5s were gloss Maserati Blue Nettuno (this became a standard Zu color after I had the first pair built in that finish). My Def2s were high gloss Ferrari red. I use my speakers for 2 ch music and incorporate a 60" display, so for movies the systems are HT 2.0. I don't find the gloss finishes distracting for movie viewing, but then again I manage to ignore incandescent 845 tubes when watching movies so any reflections off the speakers' finish is barely noticeable by comparison. Day to day maintenance is only needed if you have a household of folks who can't keep their hands off the speakers. The gloss finishes are automotive paints that are taking much less punishment than is incurred by a car out in the weather and sun. A little Mequiar's or Mother's instant clean and shine, with a clean microfiber cloth makes quick work of it. But no question the matte finishes require even less attantion.

There are a couple of things to keep in mind about the upper frequencies integration on Def4. First, you're hearing the main full range drivers up to about 12kHz, compared to a two or three-way speaker where the tweeter is crossing in anywhere from 2.5kHz - 4kHz. So most of what you perceive as high frequency performance is determined by the FRD. The new nano drivers are lighter, stronger, faster and therefore more articulate, energetic and refined than the Def2 pre-HO drivers. The spesaker's horizontal spray is also wider than before and most of the Swiss cheese effects in the Def2 soundstage are filled in. That includes the top sparkle frequencies where the Radian plays. Compared to the Def2 FRD/supertweeter hand-off, which was very good at the time of introduction and nothing to be ashamed of today, the Def4 same interface is seamless spatially, tonally and in transient character, and instead of the FRD outpacing the supertweeter as in Def2, in this case if there's preference in sheer beauty at the hand-off, it's in favor of the Radian. This is a lovely tweeter used in supertweeter application here, far better than the ribbons that annoy me, and vastly more listenable than the various and horrid metal and diamond tweeters used in some of high-end's mega-brands. The Radian uses an aluminum dome but with a mylar surround, which avoids the peakiness of most metal dome tweeters. It's not just a claim -- you can hear its extended and smooth neutrality, with dispersion more closely matched to the new FRD than in Def2.

Sidebar: 35 years ago, the Advent Loudspeaker was a great basis for building a highly credible high end system, in a market with much less choice, especially if you had the space for the Double Advent system Absolute Sound helped to popularize. That speaker produced very little worth hearing above 13kHz in a simple 2-way configuration, and spec'd out to perhaps 18kHz. At that time, Jon Dahlquist included a piezo supertweeter on his DQ10, which was flat out to 25kHz, but it beamed like a lighthouse. People did all sorts of things to improve it: wool diffusers over the piezo; replace it with a ribbon tweeter; remove it. Some people just said "....I'll keep my Advents" because they had a rightness to them without the distraction of DQ10's beaming supertweeter.

Well, listen to a Def4, or a Def2 for that matter and have two people handy to put their palms over the supertweeters while you play music. You're hearing nearly the top end of an Advent loudspeaker from the FRD's upper limit. Most of the character of the top end is determined by what you're hearing there. What any Definition's supertweeter adds is harmonic completion, further spatial cues and the subtleties of dfferentiation in expression via instrument materials, playing techniques, vocal inflection and tone. None of the Definitions added this with any ice-pick elements. The cabinet on Def1.5 was a bigger contributor to glare at high volumes than was the supertweeter. In Def2, the top end smoothed out some, but if you needed proof how much more influential the FRD is, you only had to upgrade your Def2s to the 2010 HO drivers. That put the supertweeter's relative contribution in perspective. In Def4 the Radian is a mister instead of a hose with a nozzle. But it's the new nano FRD that sets the stage for you to appreciate the Radian's deftness, dexterity and refinement.

Phil