Atma-Sphere Class D… Amazing

Looks like the disciples of the church of Bruno are laying it on pretty heavy. They decry those who cannot see with their own eyes yet ignore what they refuse to listen to with their own ears. Heresy!

All the best,
Nonoise

@facten

Nothing like high jacking someone’s thread.

If you try you will see the relevancy.

Why don’t you ASR guys start a whole other thread

Why don’t you?

Nothing like high jacking someone's thread. Why don't you ASR guys start a whole other thread

@noske 

 

I am very disappointed that the Gan guys have not taken an initiative on this. Gan is superior to silicon - so, prove it, as many others do in a variety of components and are sometimes subjected to criticism.  Everyone benefits.

110% agree. Exceptional claims require exceptional proof. Trust but verify, lol.

Here is an interesting take on the GaN device from the folks at Purifi:

Here is the opinion of the Purifi team on GaN as discussed in an interview:


Bruno: Well, with the sort of audio performance we’re getting I’d say that we’re asymptotically approaching “perfect”. One could argue that we passed the point of diminishing returns a few years ago already. I’m not saying that a next step won’t have any audible benefits, but in the grander scheme of things, the margin is shrinking.

Lars: That’s if you stick to audio performance alone. Otherwise we wouldn’t have bothered going to class D to begin with. You don’t do that for audio quality. You do that to get better efficiency, make the amp smaller and yadda. And then you get a new set of problems to fix, such as what it sounds like. And then there’s reliability, manufacturability and so on. I wouldn’t say that GaN is going to be the answer to those things, and neither is upping the switching frequency.

Bruno: Well for a given efficiency you could probably increase the switching rate, but if I’m going to shell out as much for a pair of FETs as what you’d normally pay for the whole amp, I’d rather benefit from that in terms of higher efficiency. Of course, not everyone is able to make that choice. I’ve spent my career honing control loops, most audio designers haven’t and so have to rely on simpler control loops. In that case, increasing the switching frequency is definitely helpful to reduce distortion.

Lars: We’re as fanatic about audio quality as anyone else, but because we’ve got feedback down to a T now we’re not forced to resort to higher switching frequencies.

Bruno: If we need to be geeky and I guess that the folks who are going to read this interview can handle that -eh Thomas?- lets grab the specs for the FET in our 400W Eigentakt module and its closest GaN equivalent. So that’s the FDP42AN15A0 (OnSemi) on our left and the EPC2033 on our right. Rdson: 36mOhm vs 7mOhm. Clear win for GaN here.

Lars: It’s also got a higher current rating (24A vs 48A) so if we want to be fair we should be scaling by about 2:1

Bruno: Oh erm well, that’s still a minor win for GaN because after scaling it’d come up at 14mOhm. Gate charge is of course magnificently low (30nC vs 6nC after scaling) so driver losses would be low and you can turn them on fast. GaN also has zero Qrr so you can do that if you want. But the main thing that sticks in my throat here is output capacitance. Our good old FDP42, which is from 2002 mind you, has an output capacitance at 100V of 70pF whereas the EPC device puts in a whopping half nanofarad (or 250 puff after scaling). That means your idle losses will go up, or you will have to increase dead time to allow the output inductor to recover the extra stored energy at its leisure. And isn’t it just idle losses that more or less determine real-life power consumption in full? And if power consumption isn’t something to care about, why not just stick with class A…?

Lars: And high dead time combined with high switching frequency sounds even less attractive. That just increases open-loop distortion.

Bruno: In applications like motor controllers and high density SMPS GaN and SiC devices are a breakthrough, mind you. It’s just that audio is this weird application where average power is very low and where dead time actually affects performance.

Lars: And GaN is going to mature so this picture is bound to shift at some point. Just not now.

Bruno: True. On the other hand, silicon is doing the same. More recent devices are getting frightfully close to GaN. Sadly they only come in SMD packages that require fairly expensive methods to get the heat out. Like most GaN devices. It looks terribly ancient, but the good old TO220 package is still a neat compromise in terms of performance for the price.

Lars: It’s just a game of tradeoffs. The fact that we’re using normal parts, and the reason why we chose to do so doesn’t make for a sexy story. We all like to believe in a magic bullet but when you’re an engineer you have to make choices based on tangible grounds. So the sexy story we’re trying to push about Eigentakt is that we think it’s a bloody clever design.



 

@kuribo At $20,000US, for a shiny aluminum box and a fake tube, with performance bettered by amps at 1/20th the price, I can find little to attract me for a listen.

Yes. It is imperative that blokes who are creating Gan amps provide a comprehensive and transparent independent audit of their measurements.

Failing that, it only promotes doubt as to anything that is claimed. Spot specifications are useful for off the rack retail gear.  Thanks maybe to Amir, intelligent audiophiles require a whole lot more before opening their wallet.

I am very disappointed that the Gan guys have not taken an initiative on this. Gan is superior to silicon - so, prove it, as many others do in a variety of components and are sometimes subjected to criticism. Everyone benefits.

I am not swayed by any philosophical art or flowery words. Just the facts, thankyou.

@holmz  My amps reside, with sufficient peace and dignity under the benevolent reign of King Charles III, in the country known as Australia.

Yeah @noske - which country or continent is that in which your amps reside?

Ralph did say, in and email, they are available in 230v, so I have to see if that is 50/60 Hz or solely 50Hz.

@holmz I am assuming your’s are 230v then, in addition to 50Hz?
So it would seem like you may be a long ways from Washington state in terms of shipping.
I’d kick in some $ to help with shipping if Amir has a 110-220v transformer, and if Ralph says that 60Hz is OK.

From a couple posts on AG and perhaps elsewhere, Ralph has said that he is working towards making his amps available to the wider community who have 50hz/240V power supply. I am not the odd exception, as Wiki shows here.

@aw-agd

@kuribo ...well...and that is my last comment on Audiogon, you may want to consider the fact that all amplifiers regardless the manufacturer/topology/technology will sound "differently" if one changes the load (i.e loudspeaker).

Well, that simply is not true. I have posted proof but for some unknown reason it was removed. An amp with a frequency response dependent on load will not only change character with a change in speakers but will change with the impedance changes of the speaker in use.

I’d do it myself, but I can’t because I am on 50Hz power.

@noske

Are there different transformers on the 5oHz model?
Or just a different tap point for 240v?

(A lot of newer gear is 50-60 Hz capable, so I am expecting the transformer may do both.)

I am assuming your’s are 230v then, in addition to 50Hz?
So it would seem like you may be a long ways from Washington state in terms of shipping.
I’d kick in some $ to help with shipping if Amir has a 110-220v transformer, and if Ralph says that 60Hz is OK.
​​​​​

Quite subjective. I call it a crush.

I won’t apologize for having an appreciation for excellence, regardless of the source.

I have been enjoying the Rogue Audio Pharaoh II for 2 weeks now, Tube pre section and Hypex N-Core power section. Agree with @mapman some great sounding stuff out there. 
 

Fwiw I am a long time Class D owner and fan ( well documented here).

I decided to dive into the “latest and greatest” offerings earlier this year. I went in willing to spend what was needed to put myself in the best position possible replacing older amps I ran happily for many years.

Auditioned Purify and Hypex based models and also AGD. ( had also heard those earlier, as well as many other top contenders). Decided to go for broke and tru out the $3K Cambridge Evo 150 all in one device which uses Hypex. It was a keeper.

Honestly each amp I heard knocked it out of the park. The Evo brought my entire system up to date in one shot in a smaller package for less than I had owned prior. The quality of the technology these days puts a lot of old arguments and sweating about what is good or not to rest, at least for me . I am a music lover, a hifi enthusiast and deal with technology for a living . Looking forward to hearing the Atmasphere amps to see and hear what they do. My ears are always open and receptive.  

@juanmanuelfangioii


I won’t apologize for having an appreciation for excellence, regardless of the source.

Perhaps you might try spending some time there. It would be a learning experience for you.

@kuribo that was sarcasm really do not care. We know you are a homeboy for Bruno.

ASR is missing you, 👋 

Rrr

Purifi

AGD

"While noise and spuriae are low in this design the ’traditional’ bridged Class D architecture and inductive output filtering retain some drawbacks – output impedance [dashed trace, see Graph, above] rises steeply at HF, as does distortion, while the frequency response varies with speaker load impedance [unloaded/8/4/2/1ohm = grey/black/red/blue/green traces]. Put simply, if the impedance trend of your speakers rises in the treble then the Gran Vivace will likely sound brighter, and vice-versa."

@aw-agd

Please notice how your amp has a frequency response which varies with load, unlike the Purifi, which is ruler flat.

Your amp will change character even without changing the loudspeaker!

Of course one must at last choose on one’s opinion of the sound, but for me, I expect an amp at this price range to meet certain objective criteria first and load independence is a important to me as I don’t want an amp with a frequency response/character that varies with changing speaker impedance. This issue was resolved 25 years ago or more in class d design.

@kuribo ...well...and that is my last comment on Audiogon, you may want to consider the fact that all amplifiers regardless the manufacturer/topology/technology will sound "differently" if one changes the load (i.e loudspeaker). That is why it is better to have a direct use of the auditive sense we humans are equipped with, to chose what one likes more.

Finally, for all my audiophile colleagues that still prefer reading numbers instead of listening music, I would like to remember what Galileo said "...eppur si muove.."; a very profound statemwnt despite the grave situation in which he was forced in. However, for all you, next time you may pass-by Firenze, I suggest to visit the Galilean Museum and ponder a bit when in front of the glass ball containg Galileo's hand (really, his right hand) and decipher what message he left to the posterity by using the effect of the rigor-mortis of his hand. All the best.

@aw-agd 

However as a matter of curiosity, is there a reason why in your peculiar selective cut&paste exercise you decided to omitt what in the same article the reviewer wrote about the sonic qualities and his personal experience about the sound?

I don't put any value in subjective opinions of third parties of audio equipment, especially when the associated equipment and listening environment are different than my own. In this case, the load dependent frequency response alone tells me that this amp will sound differently depending on the speakers used- all the more reason to disregard the subjective impressions.

@kuribo 

You are welcome anytime to visit us at the next Audio Show and listen to our amps and then corroborate or revisit your assumptions. However as a matter of curiosity, is there a reason why in your peculiar selective cut&paste exercise you decided to omitt what in the same article the reviewer wrote about the sonic qualities and his personal experience about the sound?

@juanmanuelfangioii

If one can get past the aethetics/gimmickry, this is what a reviewer had to say about the $20,000US version:

"output impedance [dashed trace, see Graph, above] rises steeply at HF, as does distortion, while the frequency response varies with speaker load impedance [unloaded/8/4/2/1ohm = grey/black/red/blue/green traces]. Put simply, if the impedance trend of your speakers rises in the treble then the Gran Vivace will likely sound brighter, and vice-versa.."

"a marked increase in THD into loads below 4ohm – typically >0.1% from 1-100W/2ohm versus 0.002-0.08% into 8ohm. Under continuous conditions, distortion increases from 0.004%/1W, 0.005%/10W and 0.09%/100W (all at 1kHz). Distortion also increases with frequency [see Graph 2, below] from 0.005%/1kHz to 0.07%/10kHz and 0.3%/20kHz (all at 10W/8ohm) in line with the response of the reactive output filter network."

The switching frequency is 800Khz, a bit higher than what most using silicon mosfets use (600Khz or so) but not really high enough to take meaningful advantage of the benefits of GaN mosfets. The Techniques GaN, for comparison, switches at 1.5mhz.

Load dependency is a non-starter for me. I wouldn’t call the performance "state of the art".

At $20,000US, for a shiny aluminum box and a fake tube, with performance bettered by amps at 1/20th the price, I can find little to attract me for a listen.

So here is a question, @kuribo has gone hard at the aforementioned amplifiers built by Ralph and his fine company, question is have you an opinion (yep regret that now) on the AGD GaN mono blocks? 

@ghasley 


+1. like a turd in the punch bowl.

buzzkill...

We have Kuribo claiming that only measurements are meaningful and since Hypex and Purifi have the best measurements then they are the best. Then you have Ralph saying it is ONLY certain measurements that are meaningful for sound and his amp has those measurements. Neither one of these people claim that parts and tweak execution are necesarry or important.

Please go to 10 audio.com and read the reviews of the Purifi based amps from NAD and the EVS modified VTV $1000 amp. They both use the same exact module from Purifi......I do some minor mods to the Purifi module.....but it would not measure any different. He describes the sound difference.......quite a bit better with my modded Purifi than the stock implemented NAD. BTW, I am no longer modding amplifiers.....so this is not an advertisement. In fact, you will see all references to modding removed from my website this weekend (I am sure the anti modders are celebrating....he he)

Measurements are great......I think it is better to have lower measured distortion and probably Ralph is correct about the types of distortion. But.....a BIG BUT.......this is just the beginning. I can take any amplifier of any type.....class A, Class A/B, class D.....solid state or tubes and improve the sound in infinite ways that have NOTHING To do with the distortion measurements. I have been doing this for over 40 years. People have sent me their stock digital disc players, DACs, etc. and I have done mods on them and returned them and ALL of them over the years say they now have better sound. It is universal.

If you really want to KNOW anything about what I am saying.....then simply try the transformer mod ON ANY product you have that has a toroidal transformer bolted down with steel hardware. Do you want to be right?.....or do you want to learn something? Do you want the sound you have now or do you want better sound? It will take 20 minutes to take the covers off....remove the steel and place the transformer on a three inch sqaure piece of one quarter inch thick wood. You can even temporarlily use two stacked double thick cardboard pieces Even if you just lay the transfomer down on the chassis the sound would be improved......but it sounds best by getting the transformer away from the grounded chassis.

You could also try an audiophile fuse....(the $200 Quantum yellow for instance). Does it improve the sound.....or will it do nothing as Ralph and Kuribo claim?......Who do you believe? I believe no one. I try things for myself. Do not believe me, do not believe Kuribo, do not believe Ralph......believe what you experience/what you hear. DIRECT experience tells you what is true.....words are just words.....opinions are just opinions.....truth can be known by direct experience only. Are you in LOVE? Do you need someones opinion to know you are in love? Do you need someones opinion to know what something sounds like? I hope not. Be your own Guru.....be your own source of knowledge......A wise man has direct knowledge.....he does not follow others..

We are the infinite light, love, joy and peace of God.....We are also wise and powerful....especially when we let spirit guide our ways of thinking and saying and feeling and doing. May you all create a life filled with the bliss of God.

@ghasley

Not a lot of DIY- speakers are Tympani IVa, so it will be a matter of setting up the dsp crossovers, etc. No doubt it there will be a learning curve. Not sure yet about the amps, obviously. There is a plethora of options as class d has hit it's stride of late...I may look at the new Hypex Nilai500 modules due out soon as preliminary data is quite spectacular. Those would entail a diy build, which I have some experience with so shouldn’t be an issue....

@kuribo Yes, really. As I said it is physics, not a matter of opinion. However you are absolutely right about the implementation issue. GaN Mosfets are much more challenging to use in order to take full advantage of the intrinsic superior performances. Without a deep knowledge of the device physics and experience with the device package mechanical issues, stray inductance, gate drives and overall layout, any improper implementation can demise terribly the electrical and sonic performances. But that it is also true in general since the same argument applies to the implementation of circuits with Tubes, Bipolar devices, Silicon MOSFET, in ClassA, B, C,D, E, F, G, H amplifiers (all topologies of amplifiers).

Hope my answer is helping in clarifying a bit more the subject.

@kuribo 

An informative post with alot going on here. First, I admire that you are tackling a pretty complex DIY active three way speaker system. I also admire that you've been a class d amplifier user for over two decades. Especially so given the evolution of class d amplification during that span.

Now that you have communicated you are in the market for six channels of amplification AND that you can afford to purchase anything you want....I'm still not sure that would change Ralph's mind on supplying you the data you require. It might keep him up at night that you might need troubleshooting assistance with your electronic crossover and getting things to sound right.

@aw-agd 




 

With all due respect, Silicon Mosfet cannot compete in performance nor on future FOM (Figure of Merit) improvement with GaN based semiconductors, it is not a matter of opinion, it is physics.

Really? Seems to me as a practical matter, silicon mosfet based class d amps by Hypex and Purifi clearly illustrate performance that not only competes with current GaN amps but in nearly all cases I am familiar with beats them handily in most objective parameters. One can argue that GaN devices offer inherent advantages over silicon mosfets, but unless the implementation exploits those advantages, it is all just a marketing scam. To date I have seen many GaN amp's brought to market, few that actualize these theoretical advantages.

@ghasley I simply found important to clarify to @noske, the user that called in AGD (and Atmasphere) implying a possible lack of experience (compared to Purifi) on the matter of technology, specifically on Class D and Silicon. I brought to his attention what the fact are. Is it something that is not allowed in this forum?

@noske 


 

That is quite a slab of tests. I think that someone who owns one will drop-ship one over to Amir at ASR. Probably a couple weeks turnaround.

It's quite typical these days. I can assure you most bona fide manufacturers do much more than what I have listed.

My understanding is someone has already sent one for testing, or is in the process. We should know fairly soon how it "measures up".

Yes, I am aware of Atmasphere's recent entry into the class d market. I have already previously remarked that it is an impressive feat for someone who has previously been an exclusive designer of tube amps to make the leap to class d, which I know is a whole different ballgame. Bruno Putzeys once described class d amps as wanting to do everything but make music, or something to that effect, meaning, one must overcome their inherent nature and climb many mountains to tame them. No doubt it is a tribute to Ralph to produce something which on subjective grounds seems to have attracted a following on his first go around.

@ghasley 

I assume @kuribo is a sincere potential customer

I have been using class d amps for more than 25 years. I have followed the tech with great interest over that period. I am currently putting together an active 3 way system and am indeed looking for 6 channels of amplification. With my long history using class d amps, yes, I am a sincere potential customer. I was originally drawn to class d because of its efficiency, form factor, and price/performance. While I can afford to buy whatever I like I still believe in price/performance and with class d amps with stellar performance available these days for incredibly reasonable prices, I don't think it unreasonable to expect to see performance measurements, especially for products that seem grossly out of line price-wise with other market entrants. Of course every manufacturer is free to provide as much or as little detail as possible, that's there choice. The consumer also gets to make a choice.

@aw-agd and for your first post you chose to post on a thread originated by an Atmasphere owner specifically about Atmasphere amplifiers? Were you somehow alerted to this thread by a close associate who has been following this thread?

@noske I want to assure that at AGD we are confident to provide the most advance technology with all our designs.

Personally, and to dissipate your doubts, I have been working on Class D since 2001 and on GaN technology since 2005.

With all due respect, Silicon Mosfet cannot compete in performance nor on future FOM (Figure of Merit) improvement with GaN based semiconductors, it is not a matter of opinion, it is physics. 

@csmgolf

Um, the only one in this conversation that has their mind made up is you. What difference would it make if he published the measurements? How can I reasonably answer that unless he goes ahead and publishes them? As I said, if they are an improvement on the Hypex and Purifi designs, then arguably they have an added value that may justify the 3-4x great price. Why arguably? Because "value" is subjective and as I have also said repeatedly, the ultimate arbiter is how they would sound to me in my system in my room.

I have neither seen the measurements nor heard the amp, which would be the basis of any judgments. I have remarked that the amp, UNLESS it competes on an objective performance basis with its competitors (which we DO NOT KNOW), represents a poor value TO ME at its price point. This is called "a qualified opinion" and it is based on speculation, due to the lack of data.


 

A couple of observations.

@kuribo has politely requested certain measurements be provided. He has the right to ask for those and @atmasphere also has the right to either provide those...or not. I’m not sure @kuribo would be a candidate to purchase in either case as @csmgolf has pointed out. Maybe Ralph would rather someone take the basic data he provides to make a broad decision to either go listen to them or not. Maybe Ralph could care less if the ASR crowd embraces what he has developed to even go hear them.

Here’s something that I’m sure Ralph would never do...but I suspect many others might. Why would I introduce a well made, well engineered excellent sounding amplifier at the $4-5k pricepoint rather than to exhaustively look for efficiencies and economies of scale in order to get the price down to $1k? Maybe I don’t want to build four times as many amplifiers? Maybe the money value of time to build an amplifier at the fit/finish I want to produce is X dollars and therefore I don’t want to compete in that space? My main reason to produce the more expensive product is that I simply don’t want to deal with the potential customer cross shopping Topping/Gustard/Hypex/Purifi while giving a reach-around to Amir and the other "if it costs more its a snakeoil ripoff" crowd. There are numerous examples that some potential customers simply aren’t worth the time it takes to turn them in to happy customers in order to head off the zero star Yelp review in their quiver.

I assume @kuribo is a sincere potential customer who has several measurement hurdles he wishes @atmasphere to clear before giving the amplifiers a listen. Give Ralph a little credit for reading between the lines that maybe, just maybe, the measurement police were unsuccessful in setting their trap.

@kuribo That is quite a slab of tests. I think that someone who owns one will drop-ship one over to Amir at ASR. Probably a couple weeks turnaround.

I’d do it myself, but I can’t because I am on 50hz power.

Also, what I am thinking and I may be wrong, is that this is version 1 (that I know about). AGD are already into version 2, with version 3 probably next year.

This is unlike Purifi, which is settled and been in circulation for quite some years with its predecessor Hypex and variants.

They (Bruno and his silicon mates) are miles ahead in the abundance of research, and have the starters advantage compared to a new entrant in Class D - I think Ralph's amp have only been available this year?  

@kuribo

I am not chasing my tail. If he measured all of the same things and showed them to you, what difference would it make? The better question would be, what measurement result would convince you it is a good value? You have already answered that question. The answer is, none.

You have your mind made up already. No homework necessary to come to that conclusion. According to you, the Hypex and Purifi measurements are already state of the art, which means they cannot be bested.

Just a little deductive reasoning would then show that you would proclaim it a poor value. You have your answer already and you know it. Quit playing the victim.

BTW, every amp I own is class D. I own a pair of speakers that use Hypex plate amps in them. Are they good? IMO yes. Is it a good value speaker system and do they sound really good? Yes and yes. Are they the best available? Uhhhh, no.

@noske 


Figure 1 THD [dB] vs. Frequency @ 4Ω
Figure 2 THD+N [dB] vs. Power @ f=1kHz
Figure 3 Frequency Response @ Vi=2.83V
Figure 4 Frequency Spectrum (FFT) @ 1kHz, 1W, 4Ω
Figure 5 Intermodulation Distortion @ 18+19kHz, 1W, 4Ω
Figure 6 Frequency Spectrum (FFT) @ 1kHz, 10W, 4Ω
Figure 7 Intermodulation Distortion @ 18+19kHz, 10W, 4Ω
Figure 8 Frequency Spectrum (FFT) @ 1kHz, 100W, 4Ω
Figure 9 Intermodulation Distortion @ 18+19kHz, 100W, 4Ω
Figure 10 Output Power vs. VP @ 1% THD
Figure 11 Output Impedance vs. Frequency

@kuribo It should be blatantly obvious.

No, actually. Please provide exactly what tests you wish to be performed. One at a time.

I will agree with you should you be able to be specific, rather than saying just look at the websites of Purifi and download the information provided...that is quite a rude approach to maintain.

If you desire information, it is your responsibility to request it. Politely.  I do understand that this is forum is predominately American, and I am not.

@csmgolf 

Did you bother to look at the suite of measurements published by Hypex or Purifi? Obviously not or you wouldn't keep chasing your tail asking me. Seek and ye shall find.

I have no interest in doing your homework for you. If you are too lazy to look and find the answers yourself, you don't deserve any more of my time. When you are ready to discuss the facts, let me know.


 

@jjss49   Perhaps not so weak and lame but rather the ill-considered rantings of someone who I suspect, judging by his incoherence and lack of respect for the English language, was drunk, stoned or high.  Whatever.

Exactly what is the reason that you chose to paste that rant on a thread dedicated to discussing the finer points of the Class D amp made by Ralph?

@kuribo 

There is no mischaracterization of your comments. You have plainly stated that Purifi and Hypex are state of the art and their measurements prove it. So again, what measurement could Atmasphere provide that would prove his amp is objectively superior to you? You have done an effective job to this point in this thread of not answering that question. If it can't or is even equal, in your opinion it is a poor value. You have stated that ad nauseum here. 

It seems that you are the one with poor reading and comprehension skills here. And it is pretty easy to see through. No conspiracy, no knee jerk reaction. Just calling a spade a spade. I will quote you one more time here.

You don't like it, that's your issue to deal with.

@csmgolf 

What measurement could be provided that would possibly change what is quoted here? You are already convinced it is a poor value and something that is a non-starter for you. So the question remains, why are you here other than to harpoon and tear down a product you have no interest in buying? It is blatantly obvious what you are doing. 

Simple, really. Take a look at the Hypex or Purifi web sites and download their measurements. It should be blatantly obvious.
 

I am not convinced of anything other than the poor reasoning faculties of so many who continue to make unfounded, knee jerk posts mischaracterizing my comments. I qualified my comment about value- without measurements, we can't rightly tell how it compares to the performance leaders, but assuming it is at least an equal, it would be a poor value. That's my opinion. You don't like it, that's your issue to deal with. If it performs better, then it could arguably be a better value. I am not tearing down anything except bias, misconceptions, and poor reading comprehension.

"I would not pay $5000 for an amp that offers me at best similar performance to one priced at $1000- it’s a non-starter."

I have stated that the amp, from an objective performance standpoint, provided that at best it performs as well as the current state of the art, is a poor value at 4x the price.

What measurement could be provided that would possibly change what is quoted here? You are already convinced it is a poor value and something that is a non-starter for you. So the question remains, why are you here other than to harpoon and tear down a product you have no interest in buying? It is blatantly obvious what you are doing. 

This is just my observation but the Atmasphere OTL amp products have always occupied a very unique niche, technically much different than other products.

I think it would be foolish for Atmasphere or any other smaller vendor to try to compete with Hypex or Purifi based on technical specs  because you will probably never differentiate yourself positively that way.   
 

Rather, it’s better to offer a unique option.   Like anything of unique quality, it will cost more probably than more mainstream products.   It’s like coffee wine or any other product.   There are always more niche products that excel and they usually cost more.   
 

Looking forward to hearing Atmasphere Class D amps .  That will be a draw for me at upcoming Capital Audiofest hopefully .  I have a lot of respect for Ralph . He does things his way and very well historically  .  His posts here are almost always very informative and I appreciate that