Anyone listen to Zu Audio's Definition Mk3?

These have been on my list as audition speakers when replacement time comes. But one of the things I’m taking away from the above posts is that a primary virtue of these speakers is that they play loud. Since I live in a condo and never try to listen at live levels, would it be advisable for me to remove these from my list?

No, they do well at normal listening levels as well. I too am in a condo, though Im itching for a single family home with a purpose built room, and most of my listening takes place at sane levels.

A few people have commented in this thread how the definitions come to life at lower volumes... do a little skimming, especially through 213cobras posts.

Phaelon - no offense, but I do not understand your statement that "one of the things I’m taking away from the above posts is that a primary virtue of these speakers is that they play loud." They have tremendous tone and dynamics and presence. They play big, but they do not play loud unless you crank up the volume. Yes, they are capable of loud volumes, but I never listen at loud volumes; and at night and weekend mornings I listen at low volumes. Yet, they still have the same tone, and they still have presence without being played loud. They do have a long break-in period, and they do take months to evolve. I have a 300b SET, and it is simply sweet.

Hi Gsm18439, I can understand Phaelon`s point to a degree. There are people on this thread, you,phil(213cobra) and others with perspective and opinions I respect. If you all say the DEF IV is exceptional I`ll accept that. However on 3 seperate occasions(most reccent was RMAF 2011) when going to the Zu room the sound level was stupid loud and they always seem to be playing rock or electronica(at least on my attempted visits) which made it even worse.It`s as though they`re trying to prove 'yeah we can handle loud'. It was a major turn off on each visit. I`d like to hear them at reasonable levels playing acoustical jazz or anything other than rock and pop music.
Their design and crossoverless approach gets my curiosity, I love simpicity in audio components.
Regards,

Hi CharlesDad,
I honestly think Zu plays loud and crazy music at the shows for marketing reasons and to show that they are different from the typical audiophile speaker company. I live in an old Victorian and I listen at 65-75 dB max and the speakers are really exceptional on vocals, and on acoustic instruments, and I think jazz also. Would love to hear how they compare to your Coincident speakers.

I agree with Morganc about the marketing issues. . . that Zu tries to differentiate themselves from other vendors using their choice of music. Whenever Sean Casey has been at my house, I have played only acoustic music - jazz, vocals, some classical - at very modest levels; and the sound never lacks for tone or dynamics. Actually, I never crank my Def 4s; I have an aversion to music being played loud just for the sake of loud. I have an open-plan house; while the primary listening space is at one end of the 45' x 25' x 16'(high) volume, my goal in selecting speakers was to be able to fill this space with music without having to crank the volume. I wanted speakers that could project.

Morganc,
Thanks for your reply.The Coincident model I have is really fine. Simple 1st order crossover and only 1 capacitor per speaker(no resistors at all). The Zu DEF,Horning and Ocellia(PHY drivers) are efficient-easy load speakers that seem special,at least in theory and concept.They seem to be built for music rather than current high end standard hifi(if you know what I mean).
Regards,

Gsm18439, I didn’t mean to suggest that the Zu’s ability to play loud was at the expense of all the attributes you mentioned, but rather that I was getting the impression that those attributes were maximized at relatively higher volumes.

Phil et al, can you pass an opinion on this? I'm sitting 12' from my Def4s with them 8' apart and 4' from the front wall. I've absolutely LOVED them playing cd, but have struggled a bit otoh playing lp's, to the point of distraction that no amount of altering tracking weight/speed stability/vta/phono loading has made any difference. Up until now I've had the 4s at the same layout to my 2s ie gentle toe in with line of drivers intersecting slightly behind me.
But in sheer desperation I've ended up toeing them in SEVERELY ie intersection of drivers at least 4' in FRONT of me. WOW! WHAT a difference! On analogue replay, focus has really tightened, dynamic snap has returned, and unbelievably now that I'm seeing a good proportion of the outside wall of each speaker, there appears to be minimal diminishing of soundstage spread. I am really suprised that such an extreme layout would work so well, and be needed for me to hear of their best.
So, are all of you other 4s owners settling on such extreme toe in? And why would this be so necc for analogue replay when cd replay was quite happy with more normal toe in?
I am one happy bunny, but holding off on final ok re playing lps until I experiment a little further.
All opinions welcome.

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

Hello. I just wanted to chime in with how happy I am with the pair of Zu Essence that I purchased the week before last on Audiogon. I now understand the benefits of Full Range Driver. I really love 'imaging', and am missing any so far, but it is a fair trade for how much the musician is actually right there in the room. I realize that they are not the be all and end all for definition, but here again all the music I have played is wonderful.

Of course I found this thread as my interest in Zu is heating up.....damn, I just want to be happy:)

Phil, your thoughts on toe in are spot on, I've reverted to a less acute angle for the 4s, their axes now intersect just behind the listening position. I'm still having frustrating issues dialling in analog, and am of the firm opinion that these spkrs are so revealing that components upstream really have to be performing of their best (which my tt obviously isn't quite).
I've decided to install a wall shelf to give the best inert platform for my tt, comprising, in sequence, wall brackets, 30mm slate shelf, sorbothane hemispheres, and second 30mm slate shelf. I'm confident this will give my records the shot in the arm the Def4s demand.
Can anyone out there tell me if I should be hearing anything adjusting PEQ on back of the 4s, to my ears nothing discernable.

I'm finally cracking the conundrum of the 4s, ie so much potential, but so many ways to not get them to sound that great. I've really been struggling getting esp. my tt to sound on a par with my prev 2s, and this has been spoiling my overall enjoyment of the 4s.
I've returned to less toe in, the spkrs are now 8' apart centre to centre of drivers, axes intersecting a few feet behind me, such that I can see a little of their inner walls, 14' to listening position and rear of spkrs 4' from front wall.
But, most critically, I've tamed the bass by turning the Low Pass Filter down to 40, and Volume down to 5. This has allowed bass to bloom more naturally in my space, and removed all hints of boxiness that was obscuring transparency and drawing attention to the cabinets.
The spkrs esp. on playing vinyl are now transformed, delicacy and transparency really heightened with deep bass only evident when present in material, adding that final jump factor back into the presentation.
I really couldn't be happier, aided by the fact that I'm incorporating a Symposium Isis rack into my system, really dealing excellently with vibration control.

Glad to read of the luck you've had, Spirit. My system is consistently enjoyable, but I'm not sure its always preferable to my Def 2s before I installed the nanotech drivers.

I'm admittedly poor with setup and that is likely the issue as I believe my supporting equipment to be quite good and up to par.

Any Long Island Zu experts out there want to lend a hand in fine tuning?

In most rooms, running the low pass filter above 40Hz is just too high. My LP setting is 38. Perfect. This also keeps excessive bass energy out of the vinyl mechanicals. Too much overlap with the FRD low end output if you're well above 40Hz, though can be helpful if you have a bass suck out in that 40Hz - 80Hz range.

Gopher: Next time I.m in New York....

Phil

So Phil, you set low pass filter at 38, me at 40. Where do you set volume (me at 5), and are you getting any change with both PEQ and phase settings (I'm not)?
The 4s are so revealing that I think I'm hearing my SS power amp fingerprint in the sound and am very tempted to go all tube.
I'm very aware of your preference for the Audion Black Shadow, but my UK Zu dealer also installs Atma-Sphere, and advises keeping my Hovland HP200 tube pre, and partnering it with the Atma S-30 OTL amp or even the Novachron triode OTL amp.
I have to say if choice was down to art deco looks to die for in an amp, I'd snap up the Novachron in an instant! Very little discussion of this unit on the web since it's only been reintroduced recently, but your forthright opinions on the Novachron and S-30 would be much appreciated.

That would be incredible, Phil! Hopefully by the time that comes together I'll be out of my condo and in a larger home with a semi-designated listening space, but either way I suspect the knowledge I'd acquire would be very valuable.

Thanks for that generous offer.

Spirit,

You can do better then Atmasphere IMO. I mated it to my Superflys which were a more favorable 16ohm, and despite wonderful transparency and great bass they were pretty lean and analytical.

Follow Phil's suggestions and go big big bottle SET. There are great options on the used market that will be much better then the atma.

I've never yet heard a tube amp to sound lean and analytical, BAT gear esp. always strikes me as too lush and warm.
At this point in my audio quest I have struck a good synergy between Hovland tube/SS and the Def4s, and so have to make a decision to investigate OTL Atma Sphere/Dave Berning, SET Audion, Tom Evans Mastergroove upgraded phono stage or Soundsmith Straingauge cart, or working on system wide improvements (supports/cabling/power). At present can't afford all three.

I differed with Gopher on the Atmas with Soul Superflys. I thought they were a great combo. But I was coming from the SS First Watt world, and wanted to retain some of the First Watt qualities while getting the benefits of a tube sound as well. Gopher went to the big ole 845 tubes, IIRC. So personal prefs will come into play here.

If possible, I'd try to compare the big bottle SET tubes with an OTL design.

My Hovland HP200 tube pre/Radia SS power amps are showing a good synergy with the 4s, and I'd really need to be convinced of the benefits of all tubes to make the pricey step up.
In the UK it's getting harder and harder to make meaningful audio comparisons, so I have to grab auditions when I can.
If I move from the Hovlands, my likely alternatives are the Atma Sphere S30/M60/Novacron or Dave Berning OTLs, and Audion Black Shadow 845 SETs.
Simon, the UK distributor of Zu really rates the Atma S30, maybe this is where I'll end up, certainly will be my easiest to arrange audition.

Gopher,
Your big tube SET vs OTL comments are astute.These are two different camps for sure.Preference and system will determine which direction to go.
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

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,

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.

You can do better then Atmasphere IMO. I mated it to my Superflys which were a more favorable 16ohm, and despite wonderful transparency and great bass they were pretty lean and analytical.

Follow Phil's suggestions and go big big bottle SET. There are great options on the used market that will be much better then the atma.

A customer's comments that seems to have some relevance:

http://www.atma-sphere.com/AboutUs#Feedback

Schw06. . . What spikes do you and other Altanta Def 4s use?

Atmasphere,
No surprise, some will love your amps and others have tried them and selected something different(preferences being what they are).I suspect most of the amplifiers mentioned so far have a legion of happy customer testimonials. Variety of choice is a good thing.
Regards,

Gsm18439,
We are all using Star Sound Technologies stands. 3 of us are using the Sistrum sp-101 and the other is using a smaller stand. A call to Robert is free and he is generous with his time...A real eye (and ear) opener for me. I have Agear to thank for the suggestion.

Agear. Who is he LOL. I got my balls busted for the upgrade Sistrum stands thought here on this thread on the Def2 speakers.

Doc to Doc how can I compete with that?

We have the Atma S30 on the Def2 and it is an outstanding match. Not lean at all. So David has some good thoughts on different amps that work on the Zu speakers.

Only issue we have with the S30 is it is noisy. Sending it to Atma did not heal it.

You reap as you sow Mr Anderson.

Did you ever have the Defs on Sistrum or just Equarack and Stillpoints?

Some of you folks might want to check out Ingress Audio isolation roller blocks. I installed them on my Superfly's and they made a big improvement.There are some pics on the Decware members system pics.

Correction,the pics would be on the Decware General Discussion & Support page.

Here is a link to another thread here on the 'gon:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1220502548&openflup&27&4#27

He is using ZUs.

Setup is everything when you have speakers like this. If you also combine that with an OTL, you will have a very revealing system. The problem is that it might reveal more than you want to hear!

One of the bigger problems we run into is someone gets our amp(s) and then does not realize that their digital gear is really not all that great. The S-30, like all OTLs, has lots of bandwidth. It reveals poor digital gear for what it is.

Now some people might think that this is the fault of the amp but its not- revealing is revealing. Most SETs lack real extension on top (unless they are very low power), and due to their even ordered harmonic distortion, they sound quite rich (the ear perceives harmonic distortion as tonality...). SETs often add some of the missing harmonic richness that bad digital is lacking, plus smooths over the raucous high end. But it would be a mistake to think that that is musically right.

Now if your digital is working properly or if you play analog the S-30 will come off as quite relaxed, plus you get more detail (and in case anyone has got the wrong impression, this is true if you have a good SET too). 'Relaxed and more detailed' is the result of less distortion; ultimately you get more music.

I can't thank everybody enough who has taken time to contribute to this part of the thread. What I'm finding with my Zu-Hovland combination is a great synergy, but the 4s are so revealing that I believe I'm hearing the sonic fingerprint of my Radia SS power amp as a slight steeliness/edginess where the leading edge of notes is at the expense of the full bloom of notes. It's just a hint, but I suspect that all tubes will take me in a better direction. In all other respects I love the combination. Interestingly my cd player sounds better than ever, but I can really "hear" the mechanical nature in digital clearly not present in analogue reproduction.
It's getting harder and harder to audition all types of equipment, esp. if like me you don't have a relationship with a single dealer.
So I'm going to spend plenty of time (and perhaps not a little cash) investigating SET 845 v OTL, in the form of Audion Black Shadow v Atma Sphere/Dave Berning. Luckily all three brands have good representation in the UK, and all three have the thumbs up from those who've heard them with the 4s (Phil re Audion, UK Zu distributor Simon Matanle re Atma Sphere, and Roy Gregory who reviewed the 4s for Audio Beat re Berning).
A lot of other repected choices don't have UK distribution, so it's down to these three.
Loathe to replace my Hovland HP200 tube pre, this I really do believe to be liquid and revealing, and has benefit of remote control.
I'm really craving even handedness and neutrality, so I want to make certain that any extra tonality that might be present in SET over OTL isn't a colouration taking me away from this goal.

Spirit,
Your decision to audition all three of these amplifiers is wise.You`ll get endless opinions from the rest of us based on our own experiences and personal taste. Only you have your unique pair of ears and this is the best way to choose what`s best for you.I`m sure builters of SET amplifiers(or any other amp topology) could make their case as passionately as Ralph naturally does for the merits of his OTLs.Listening will settle it for you.
I look forward to your exciting endeavor.
Regards,

+1 to the last comment. In a big way. At some point it is all about hearing something in your system and seeing how it meshes with your room, equipment and preferences. Let us know how it all turns out.

A little info that may explain the assertion that the 4s with OTL sound possibly lean thru the midbass, and analytical with emphasised treble, versus SET 845 which may present more body and a richer tonality.
It seems that the capacitor, a Mundorf, on the high pass filter to the Radian tweeter would present a very hot treble thru the Radian 850 with OTL.
A solution to this would be the replacement of this capacitor taming the very top end a little to accommodate the OTL more successfully.
Apparently this is a rel simple job involving getting to the back of the tweeter, the capacitor is not even soldered, just a straight swap.
Interestingly on the 6Moons preview of the Druid V, the Italian distributor has done just this proceedure to alter it's high end character.

Spirit,
I reccently replaced my speaker`s only pair of caps(tweeter)with the Duelund CAST and they are simply remarkable! Keep in mind an upgrade crossover capacitor will benefit 'all' good amplifiers(you`ll hear more of what it has to offer).What is your replacement capacitor?
Regards,

Charles, not sure. All I know is that Simon the UK distributor who is a big fan of Atma Sphere certainly agreed that the hint of leaness with these OTLs could be effectively countered by a cap slightly holding back the top end and accommodating the OTL more sweetly.
I believe the 4s use Mundorf, but this isn't my field of expertise, so will leave to Phil to contribute if he wants to.
Personally, the sound of the 4s is changing for the better every day. They're really chameleon like, absolutely reflecting what's on the recording, not imposing themselves, and presenting a real open window to performance.
My Hovlands are sounding more and more like they're keepers with the 4s, but I'll keep an open mind re amp choices.