Atma-Sphere Class D… Amazing

Blushing, I was kinda jesting about point 1.  Testing equipment is of course more than sufficient, and Ralph's considered comment is important.

I would also point out that the transition from most tube amps to Class D amps is probably more challenging for owners than most. Most speakers that sound good to someone with a tube amp will sound different with most Class D amps. As they would with most SS amps that also tend to have much lower output impedance and are also capable of driving more speakers well. Given that, I still suspect most tube amp lovers will be more pleased moving to a good quality modern Class D amp than others. But still in many cases, a move from tube amp to SS amp is also likely to involve a speaker change unless the listener is able to make the adjustment. I suspect many cannot.

Perhaps the Atmasphere Class D amp, coming from a vendor known for their OTL tube amps, is a more natural path to Class D for tube amp owners? One that is less likely to make owners jump ship on speakers they selected to sound good with their prior OTL amps? That would make sense. Just guessing though...have not done the homework yet on the Atmasphere Class D.

In any case, it is not possible to properly assess any amp without also considering the speakers it will be driving. The best amp/speaker integrations will ALWAYS produce the best results. Nothing else is possible, though some amps will care less about what speakers are used than others.

I would also point out that the transition from most tube amps to Class D amps is probably more challenging for owners than most. Most speakers that sound good to someone with a tube amp will sound different with most Class D amps.

Most loudspeakers are meant to be driven by a voltage source which is an amplifier that either doubles power as the load impedance is halved or cuts power in half as the impedance is doubled (tubes, if acting as a voltage source, do the latter and this does depend a bit on which tap is used on the output transformer).

A small number of speakers, but significant in high end audio, are meant to be driven by amps that behave more as a power source rather than voltage source (SETs are an example). The most likely embodiment of this is a tube amp that runs little or no feedback. Some of these speakers have level adjustments (meant to allow the speaker to be adjustable to the voltage response of the amplifier) on the back, like my Classic Audio Loudspeakers. If these adjustments are present they will have to be set up correctly but the speaker will accommodate both types of amps. Another example of this is the Sound Lab electrostatic.

@atmasphere

A lawyer might ask, in a court of law, ’which is it? Were you lying then or are you lying now?’ 😁 I’m not suggesting that you’re lying; I am suggesting that its impossible to be truly objective.

Subjective opinions can carry quite a bit of factual information. If all those opinions say the same thing and the people producing them are unaware of each other they carry quite a bit of weight. It seems to me that you’ve still not made the connection of how important measurements are to the subjective experience (and I see that all the time on the subjectivist side as well...). The rules of human hearing are the reason why; as I pointed out earlier all humans use the same perceptual rules. So if we can sort out what’s important to the ear, then we can make the measurements to show if we’ve made progress. The former is the tricky bit!

If you believe that there is factual subjective information contained in the measurements, then wouldn't that be reason enough to publish them?

I don't believe that the subjective opinions of others carry factual information for 3rd parties- that is the nature of subjective opinion by definition- they are feelings or thoughts based on perceptions. Opinion are not facts.

You can amalgamate opinions of a group and develop a model of group tendencies and use it to predict consumer behavior, the basis of market research. But that will never tell you with any real certainty if Random Joe will like your hot sauce. I don’t buy based on market research- I try for myself. And I know many people that aren’t going to pay $5000 for an amp because a group of people on an audio forum says its s’wonderful! They will want to hear it for themselves in their system, in their space. I also know many people who wouldn’t even consider an amp at $5000 without seeing the measurements first.

Yes, you have previously mentioned Fletcher-Munson curves and other such models of aural perception. I have made the point that all of these models you bring up are empirically derived from testing. As a result, their predictive power is only as good as their assumptions and test subjects. I have made mention of the fact that the Fletcher-Munson tests were based on subjects described as young subjects without hearing deficiencies- not really representative of this forum’s members. Also, as empirically based models, they are predictive of group tendencies as they are constructed around average responses from a sample. In other words, they have weak predictive power for any random individual. Again, as I mentioned earlier- for a manufacturer trying to reach a large target market, these models are useful. On the other hand, for an individual user, they are not going to tell you anything with any real certainty. I have made this point on numerous occasions but have yet to see you address it.

All opinions don’t say the same thing- how do they carry "weight"? What "weight"? In whose opinion? Opinions about products are all over the map- that is proven here every day. It is also proven by a market full of successful amps of every sort of class, type, and performance level. There is no one clear winner- there are many successful products which cater to different market segments- tubes/class d, vinyl/digital, cables matter/cables don’t matter.

What’s important to the ear? The ear is just a transducer sending a signal to the brain. It’s how the brain interprets the data that matters. Science tells us we don’t all interpret our perceptions in identical ways- there is variation based on numerous factors. No model is perfect. After all, the Fletcher-Munson curves have been revised repeated over the years.

No, I beg to differ as to the value of other’s subjective opinions when it comes making individual choices and the value of your claims regarding the predictive power of perceptive models on an individual level. Look no further than the marketplace.

You are aware no-one is going to beat Bruno’s numbers any time soon. For that reason alone I really don’t see what you are so concerned about what measurements we get.

Why would your measurements need "to beat Bruno’s numbers" in order to be of value to a potential customer? You claim there is a strong link between the measurements and subjective performance- so why not show how exactly?

Yours is a GaN amp and I presume you chose GaN fets for a reason. I would think you could demonstrate through your product’s measured performance exactly what advantages your product has as a result. You keep talking about distortion spectra and subjective perception of sound. I, and I am sure others, would find these measurements of your amp informative. It’s a competitive market place with many options available to consumers looking for state of the art amplifiers. Clearly you aren’t trying to compete on price, nor does it seem you are attempting to compete on objective performance. I can only assume that you are competing on subjective performance.