Anyone listen to Zu Audio's Definition Mk3?

Charles, excuse my ignorance, but what are the salient differences between the two tube camps?
I had never got on with tubes full stop, being totally put off them by the stereotypical over warm wooly sound portrayed by BAT eg. But seven years ago got bowled over by the tube Hovland HP200 pre and found this sounded great with the SS Radia amp, servicing my Pro Ac Futures 2, then Zu Def2s and now 4s. Just love the combination of tube liquidity and SS neutrality.
Interestingly the 4s are so transparent and revealing I'm detecting a hint of hardness/coolness which I attribute to the SS Radia, and am really tempted to investigate all tube. Let me say this hardness is only a hint and may well be eradicated by careful choice of cabling (considering all Zu Event) rather than amp change.
So we have SET eg Audion Black Shadow, championed by Phil v OTL eg Atma Sphere championed by UK Zu dealer/Dave Berning ZOTL, much favoured by Roy Gregory in the detailed review of the Def4s in Audio Beat.
How do their respective pros and cons stack up, esp. in respect to listening thru the Def4s, with a very neutral revealing front end (in my case direct rim drive tt with air bearing linear tracking arm Trans Fi Salvation/ Terminator T3Pro)?

Hi Spirit,
I could relate to Gopher`s comment based on my own experiences, but keep in mind system synergy is key.I find the Atmasphere can come off very clear,fast and transparent but also lean and thinner in some systems.In comparison the 845 SET ampsI`ve heard are fuller in body and tone with more presence and flesh on the bone,yet as detaied(not dark,slow or veiled).Depending on one`s needs or wants 'either' could be the right choice.

Some will say the SET has more pleasing distortion(2nd order)to account for this perception of fullness of tonality.Maybe, but I`m always struck by the full body and warmth of tone when I hear live acoustic instruments(they are`nt lean nor lacking color-tone saturation).Depending on speakers,room acoustics and other components the Atmasphere could be ideal.

Given the nature of your speaker I suspect a fuller bodied SET could mate well with such a revealing and transparent speaker(just a guess). Obviously there`s no better solution than to hear both in your system.The good SET amplifiers as has been stated before, are also very transparent,nuanced and also 'fast'.Hard to predict which one a listener may prefer.
Regards,

Spirit,

To answer your questions directed to me:

I had OTL amps for a long time (pre-Zu) and I did listen to an Atmasphere amp on my 1st-gen Definitions before buying Audion Black Shadows. At the time I was using Audiax 88 monoblocks. OTL amps are highly transparent but if push-pull, they still sound like push-pull amps with that subtle crossover notch grunge. You only really notice this once you live with the unity of fast, transparent SET like Audion, and then try to go back to push-pull.

With Zu you don't have to. You have the efficiency for 25w to sound robust and with 845, you get quality bass with the rest of its convincing tone. Other than what someone qualified might homebuild, the synergy between Zu and Audion SET, and a few other similarly-voiced alternatives, is elevating to both.

As I've written before, once you have a Zu speaker the fulcrum of fidelity for your system is the power amplification. It's worth getting right before pouring more money into sources and cables, especially if you have credible bits there already.

Sonically I put the Berning ZOTL scheme ahead of Atmasphere. However, if you feel truly satisfied with your Hovland combination, build on that. I think Black Shadows with proper tubes, into your Defs, will alter your perception of what's satisfying.

Phil

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,