What class of amplifier has the most high definition sound ?

For those experienced audiophiles, wich know all kinds of amps, may say what class of amp is better defined in therms of PURE SOUND?
Of course the sistems are compatibles for comparisons.

The Audia Flight Stremento Mk2 is class AB is one of the best made  and best sounding solid  state amp made. 
sacresta what does pure sound mean? 

Do you mean uncolored, dynamic, bass slam, treble extension.

There are uber high resolution amplifiers Solution, Spectral, very low levels of coloration

and there are warmer reference amplifier lines Vitus, T+A, Darhtzeel, Dagastino, Pass. 

Generally speaking, class A will have the lowest distortion and thus the 'PUREST SOUND'.

Generally speaking, because execution can play a pretty big role in the results.

BTW, the **kinds** of distortion can be more important than the amount; 0.005% THD won't do you much good if its all higher ordered harmonics (which is often the case with THD figures this low) since the ear uses higher ordered harmonics to sense sound pressure. For this reason the ear has to be extremely sensitive to higher ordered harmonics and so is more sensitive then the best test equipment!

Recently, class D has begun to show promise as an amplifier technology that can lack the higher ordered harmonics. When amps don't make higher ordered harmonics, they can sound very relaxed with great detail, such that you can listen to them all day. This BTW is the foundation of the tubes/transistor debate...

So if one is being pragmatic, there really isn't a one-word answer to your question.

I would say OTL class A
 I have a pair of atmosphere M60s and they impress me greatly. I have a owned class a, regular tube with transformer, class AB. 

You can't really say amp without including the speakers in the loop. And you can't really say speakers without saying room. For me, only using one cap in my crossover, my answer is going to be different than the person using complicated drivers and crossovers.

Recently I'm a class D guy.

Michael Green

Post removed 
Audio Research.

Says so right there on the front panel, can’t miss it.........
When I joined the single ended tube amp cult (the meetings surprisingly  require elaborate disguises and often feature meaningless chanting) it was sort of an experiment as I became curious about all the fuss and mythology about these amps, so to speak. The tonal palette revealed in the amp I wound up with, a Dennis Had hand made little 12wpc gem called an Inspire Firebottle HO (high output), was a surprising and simply a game changer. I'd been using a classic push pull tube amp for some years prior to the Had amp, have owned countless nice SS amps, use tubed guitar amps for over 50 years, and still...blown away by the Had. Paired it with relatively efficient (alleged 91db Silverline Preludes, 93db Sonist  Recital 3s) and although preferring the Preludes over the Sonists tonally I was compelled by curiosity (again) to try Klipsch Heresy IIIs with the 8ohm nominal 99db efficiency. Added a tube preamp, and am happily enjoying the rig on another level entirely...tied to efficient speakers, el tubo a mundo, and enveloped in a self indulgent smugness about the whole thing. 
Practically, high efficiency good quality Class D amps are capable of delivering the most high definition sound with the widest variety of speakers.

Otherwise, at the other end of the spectrum, low efficiency Class A amps can do the job very well also but you typically need larger, higher efficiency, easy load to drive, and typically more costly speakers to get the deed done.

How loud one need go is another key factor. A lot of detail listening is done practically  at modest volume, which is a lesser challenge for most amps.
Please define "high definition." I have no idea what is meant by "pure sound."
Though I haven't yet heard one (soon to be rectified), I am curious if the answer turns out to be a direct-drive tube amp driving an ESL loudspeaker. No amp output transformer, no ESL step-up transformer---sounds very promising, right? An OTL driving an ESL gets half the way there, but that designs (generally) somewhat high output impedance brings its own potential penalty.
"High definition" is very much dependent on design.  Except for the hopeless designs of Class D.  Nothing can bail out a design that is so fundamentally flawed.
I can't believe no one got that.......

Didn't you hear the groans, Ozzy?
I would say OTL class A

Ditto that.
But there aren’t any speakers "THAT I LIKE" yet without any colorations that they can drive with ease (without bandaid fix autoformers), top to bottom, so "TO ME" your ****** if you do and ****** if you don’t.

The only way is to make a hidiousely big OTL Class-A with a bazillion tubes, so they could drive hard to drive speakers speakers that are designed to be flat, low coloration, low distortion and without horns to make them efficient.

Cheers George
Class A, since there is no crossover distortion of any sort.
NO OTHER CLASS can beat it.
BUT....... class A runs extremely hot & inefficient.

Pass Labs are the best example.
The question was about the *class* of amplifier. And -- if cost i no object and all other variables held constant, class-A, no question.  But it has many downsides, mostly size, heat and cost int he real world.
For small signals anyone who doesn't design class-A is crazy. For big power amplifiers there are many trade-offs. Note there are also sliding scales.
Class D, an entirely different type of "class" has huge potential but still needs refinement. Modern GaN is already helping.
But among A, AB, C it is clearly A.  That said i always design high bias AB for bog amps.

Only opinion:
High efficiency speakers with a First Watt amp.  
Ok guys, my question was focused in experience and sensitivity to pure sound.
Class A, A/B, D ? High definition or pure sound are subjective concepts.

I didn’t ask for brand or speakers quality. I said compatible system!

Thanks you all.
"They" say that SET amplifiers are the best but since I have no experience with them I cannot confirm or deny it. But "they" say lots of things that may or may not be nebulous. In general I consider vacuum tube amps to be superior for audio reproduction but others swear by solid state. I suspect it all comes down to individual ears as I’ve proffered before.....different folks hear differently just like how some folks can see better than others. Perhaps one day we can all be able to say "I see the light."
That is not  clear  cut at all, a SET tube amp with very efficient speakers may have the best purist  midrange,  and a big solid state amp  may have the best dynamics or Bass. The speaker 
and type of music too come into play.  The correct answer is
No amplifier is the best under all circumstances .
I can't believe no one got that.......


Heh, I got it.....dilly dilly. My CD player says on the front :"vacuum tube reference CD player" but I don't know what the reference was. I sometimes listen to it , though.
It doesn't matter for as long as you plug them in Furutech duplexes because this completely eliminates all distinctions.
 Everyone knows that Class A is best.
sacresta OP
Ok guys, my question was focused in experience and sensitivity to pure sound.

"Pure Sound"?? Class-A OTL tube wins, with heavy proviso's on what they can drive. After which come Class-A solid state, which can drive most things if good designs. 
SET and all other tubes are governed by their output transformers, they are not "pure in sound" and have colourations.

Cheers George
To win, you:
1. can't have an amp with crossover distortion (sorry class AB)
2. can't have an amp that isn't linear & has an output filter (sorry class D)
3. can't cheat and use a bunch of feedback to lower distortion. (sorry class AB & D).

What we are left with is Class A solid state for accuracy (pure sound?) and tubes for adding those lovely harmonics that give us that deep and wide sound stage, extra decay, and rounded notes. 
I would say it somewhat differently - tubes presenting harmonically correct soundscapes.
I would say it somewhat differently - tubes presenting harmonically correct soundscapes.
Only Class-A OTL's, anything with an output transformer is hamstrung.

Cheers George 
The question does hinge somewhat on what you intend to drive. A SET can measure great into a 16 ohm resistor. It would crap it's pants driving my Focal speakers though. 

I don't consider feedback a universal evil. Like anything else, it requires proper execution. 

Class D is out of the question, DOA, given it's gratuitous complex distortion at low power levels. Class A simply destroys class D at 1 watt where a huge amount of detail resides. 

what class of amp is the High Definition kind?

short answer? The High Dollar kind.

almost invariably greater fidelity goes hand in hand with more investment. despite ‘class’.

A, A/b, D, Hybrid, Tube amps which have an enormity of classes based on their output tubes, all have different levels of audio definition, or resolution. as the entry fees escalate in each camp, usually their resolution increases commensurately. there are over achievers and we all seek them out, but usually, more money means better most often. 

 the buyer beware note here is that it will take more than just an amp to realize the amps true abilities.

there needs be a great source, and of course, great speakers, or at least very competent ones.

a pair of Hiesenberg monos at $100K running into a pair of say, Joeseph Audio Pulsars isn’t gonna express the entire bandwidth as revelatory as they would with say, a pair of Legacy Aries.

amps are key, but so is the rest of the rig.

If there was a magic bean, don’t you think we would all have one?  Many choices, many tradeoffs and associated gear is among them.

The unstated inference is that anyone who agrees with what the magic bean happens to be, is dumb if they can afford it and don’t own it.

I found the match I like for my planars and understand others enjoy their amp for efficieny speakers.  There is no one size fits all “best”, no matter how much money you throw at the issue.  For those of us on a budget the choices are fairly proportional to the budget size and associated gear.

There are many great combinations at a variety of price points.  But alas, there is No magic bean.
I believe in Dilly Dilly.  

@georgehifi -- have u looked at Audiokinesis?
I read all this stuff about Class A and thought it was overblown, so finally bought the 8-watt Pass Amp Camp Amp from diyAudio store. Built it, used a Marantz receiver to drive it, and thought, hmmmmm, that’s pretty sweet. Not much volume into 89-dB speakers, but very “natural.” That’s my adjective for a sound that approximates an acoustic sound. A piano sounds like a piano, not a keyboard.

so I built another ACA for monoblocks, so now 15 watts a channel and good volume. I really like my Rogue Sphinx Class D into Magnapan 0.7s, and also my old Marantz, but I will say there’s something special about Class A. My experience.
@sacresta, I think I know what you mean by high definition and pure. That was my first reaction when I first heard a Class D integrated. It was a Primare I32 and it may have been due to their unique and proprietary implementation of Class D. I've never heard any other Class D, so I can't say; but defined and crystal clear was the way I described it. As a frame of reference, to me most tube amps sound sweet and mellow.
I would say that Class D and Class A tube amps (excluding OTL) have an opposite sound signature. 

Tube amps add some meat to the bone.

Class D amps take some meat off of the bone. It can come off as crystal clear, defined, and completely quiet between notes (inky black) but to my ears that sound signature is the result of removing a tiny amount of the music from the source. My guess is that its a product of the output filter, a tiny amount of the good leaving with the bad.  
If my SEP (that's right, P!) amp is being strangled by the output transformers (or is it the input transformer acting in a co-strangle mode?) it must be consensual and a good thing somehow as it's the best sounding amp I know of, or certainly have ever heard in my various systems over the years. Good job transformers, whatever the hell it is you do...
This thread,
Pit of misery,
Dilly, Dilly!
Good job transformers, whatever the hell it is you do...
They provide the even ordered harmonics (distortion) that makes tube amps sound so nice. 

I'm pretty sure it's the tubes that do that, as it's been claimed the transformer's job is to strangle things. You have to pay attention around here.
Class D amps take some meat off of the bone. It can come off as crystal clear, defined, and completely quiet between notes (inky black) but to my ears that sound signature is the result of removing a tiny amount of the music from the source. My guess is that its a product of the output filter, a tiny amount of the good leaving with the bad.
"a tiny amount of the good leaving with the bad."
The bad being "switching frequency noise".

Trouble is, there’s still a lot of the bad left behind, with today’s Class-D topology.

Best, least coloured, fastest, cleanest, most dynamic a Class-A OTL tube amp, trouble is the speakers they love to drive are the "polar opposite" if full range 20hz-20khz.

Cheers George
Transformers provide nonlinear frequency response, not second harmonic distortion. One sucks, the other rocks. Why wouldn't you want to just connect the output devices directly to the speaker? That just sounds smart on it's face!
Ear 868 preamp,Ear 509 power or 890,.
Audio Note M5 and GamuT D 200i
Integrated: Gryphon Diablo 300, Isoteric 03/05.
Wrong question. It is related to results but does nor answer your question.
Operating class is not a value graduation, while applicable to RF amps not so directly with audio. All low level stages are operating in class A, i.e. full current, they only need to amplify voltage with no demamds for power. Only the output stage adds current to the formula. Here the biasing class determines the zero signal current of the output stage. Biasing needs to overcome device non-linearities at lower idle current. More current is more heat and power wasted, less for output. Heat loads increase adding demands for heat sinks and bigger power supplies.
So there are tradeoffs. 5W class A or 15W class AB?  Class D is not a biasing class, just a diffent amp architecture. Output stage is like switch mode powersupply, either fully on or off. The magic happens at the input where the switching levels are determined. Anything other than pure DC in the power supply will end up in the output just like any other amp class. 
Focusing on bias class is a waste of time. Find a good pairing with your speaker is more important. Difficult speakers will reduce the choice of amplifiers. Shun those 85dB speakers.
Good dynamics means high efficiency with budget in mind.  
Georgehifi: Best, least coloured, fastest, cleanest, most dynamic a Class-A OTL tube amp, trouble is the speakers they love to drive are the "polar opposite" if full range 20hz-20khz.

+1 for the first part of that sentence.

I love my Atma-sphere MA1 amps. Clean OTL class A. I had the marvellous Krell FPB600 but have not looked back (much).

Speakers? You can get them. OTL amps can play the full frequency scale ok if the speakers are matched. And if the speakers aren't tuned to the amp, you can forget most of the discussion about amp quality, class A B or what.

For OTL you need easy to drive speakers, 8 ohm is marginal, speakers should be 12 ohm or more, OTL loves 16 ohm speakers with 90+ sensititvity. If not, your money on the OTL amps are wasted, you will get good but not excellent sound. 

I bought Audiokinesis Dream Maker speakers, and have been very happy with this combination.
What class of amplifier has the most high definition sound? 

The one that you want, but don't own. ;) 

Having built all manner of audio systems I assure you that the caliber of the system build has as much influence upon performance as the amp (or class of amp) itself. 
D_Schroeder wins #micdrop - BOOM!