Anyone listen to Zu Audio's Definition Mk3?

Within any particular "camp"-SET, OTL, pushpull pentode, solid state--there is at least the same amount of variability in sound as between the camps. I can think of quite a few tube amps that sound leaner, and more brittle than the vast majority of solid state amps.

I agree that the Atmasphere OTL (which I like a lot) is on the leaner side (not as much upper bass as many tube amps), but that is hardly an OTL characteristic. For example, a Joule OTL is a much warmer sounding alternative. I don't think one can get the same kind of liveliness and "jump," combined with reasonably high output, as one can with a good OTL amp.

SET amps can be very nimble and dynamic sounding, WITHIN their admittedly narrow power delivery range. With the right speaker, a low-powered 2a3 SET can sound far more alive and dynamic than almost any solid state amp and can hang with OTL amps.

I had a First Watt amp (J2?) in my system for about two weeks. I liked the sound--clean, clear, grain free and musical. But, the sound is still easily identifiable as solid state--slight "edge" to the initial attack of the note, not as spacious soundstage, less of a sense of ambient "fill" and natural decay of notes. I would have no problem with living with that particular sound, though I prefer my SET and low-powered pushpull amps.

With really good low-powered pushpull amps, I don't hear any "grunge" to the sound--I get plenty of clarity and a very tight punchy sound. But, the tight bass also sounds a touch mechanical (bass tends to sound the same regardless of the recording) and less tunefull and differentiated than with good SET amps. The "cleaner" sound also seems a bit devoid of ambient "fill" and natural sounding decay of notes (whether these qualities are artificially created distortions of SET amps, I really don't care because I like them). Still, I like the sound of certain pushpull amps a lot. I am currently running a great sounding pushpull amp that puts out a whopping 5 watts per channel that sounds fantastic.

Larryi,
Hey, nice post and I agree with your overall descriptions of each amplifier type.None of them are flawless and each will have its attractions. Your characteration of SET amps(the good ones) is quite similar to my experiences.

"ambient fill and natural sounding decay" is a quality they posess that I find difficult(very) to live without.They score highest on my 'realism meter' as a result. I agree with phil, you don`t have to sacrifice transparency,speed or natural detail or resolution.Spirit, how likely the chance for a Audion -Atmasphere comparison in your system?
Regards,

Siprit,
Have considered Gopher`s 211 tubed Melody AN 211? It has great word of mouth praise and is`nt uber expensive.
Regards,

My issue with SET and Zu has been that the bass just isn't right. This is why I chose Quad II 40s over Audion Black Shadows (with in-home auditions). I think everyone in Zu-land needs to try out several topologies to find out the best match in your room and with your taste. Funny that every single person on this thread has a different amp--that says a lot.

And for bass, Tron soundtrack by Daft Punk Track #2 is my reference. Highly recommended.

Everyone who knows me knows that I have been drinking the Zu Kool-Aid for years now. I agree with Phil (213Cobra) that finding the right amp is fundamental to building your system around the Definitions. Having patience and willingness to try numerous topologies will give you the best chance to find the best match for you.If you are buying the Definitions or planning on it, my suggestion is to plan to experiment to find what pushes your buttons. "one and done" is a very unlikely approach. We all value certain playback features differently and that shows with the great variety of amps Definition owners use. Try every amp you can on the Definitions. The great part about them is that just about every amp on the planet will drive the Zu's to satisfactory levels. I believe I have heard every topology on the Defs and I can see why some would want OTL's, 845 SET, monster SS, chip amps etc...They all have strengths and weaknesses. Nobody can choose for you. Be adventurous (and report your findings back).
That being said, there is one area that most Definition owners neglect and, to me, the first component to address (even before trying to find a matching amp): the speaker foundation. Replacing the stock spikes with a proper foundation unleashes a whole new level of performance that will be appreciated from the very first note. There are 4 Definition owners in Atlanta and we all own the same speaker stand...Obviously not a coincidence. I feel confident speaking for all of us that it was money very well spent. For me, it may be the biggest performance upgrade of everything I have tried(which is a looong list). Sounds ridiculous...I know.