My audio experience is quiet extensive, going back some 30 years before I was a partner in Audio Tweakers in the early 2000s.
@tweak1 I don’t have a dog in this fight but if I can offer some advice? I’ve found personally that testifying to however many years of experience I have really amounts to nothing. That isn’t how you develop cred. Also, in this particular case @kuribo has a point that isn’t being addressed by the attacks on him.
Its a simple fact that if you are a designer, you have to have measurements to confirm the authenticity of your work. I imagine a lot of people expect that our OTLs are a pretty tweaky amp, after all they have only one gain stage, are fully balanced and differential, are all-triode, class A(2) with a direct-coupled output and no feedback. That’s a mouthful and I expect that many people imagine us sculpting the sound (voicing) with certain exotic components, special wire and so on.
But we don’t do that- we rely on the measurements; if the amp fails that there is no reason to listen to it. We don’t tweak it for sound, we tweak it (if that is even the right expression) for measurable performance. More often than not, that likely involves changing a resistor value to fix an operating point of a tube...
Producing our class D amp would have been impossible without the measurements and of course the underlying math!
So for @ricevs to really address kuribo’s arguments, producing the measurable improvement in performance is how to do it. Failing that, using the argument that the ear hears more than we can measure (which is a false argument now, though probably true 30 years ago; like those that strive in so many different fields we audiophiles tend to live our lives based on tradition and what we learned long ago rather than using up-to-date knowledge) really isn’t going to wash! Why? If it sounds ’better’, why does it do so? Is it lower in higher ordered harmonic distortion? Perhaps less phase shift? Not knowing the answer is really a terrible thing!
Put another way, if you cause your hand to move and actually make the measurements that will answer that question (and one valid excuse might be that the test equipment needed to do so is a bit expensive) you should be able to sort out why it sounds ’better’, and now you have a concrete argument for the skeptics.
As an example some decades ago I found that the power cord could have a dramatic effect on one of our amplifiers. That really bothered me since I didn’t know why. Since it affect the sound of the amp that provided an access- so I measured the power and distortion based on the one variable of two alternate power cords, one ordinary one and one that was more ’exotic’ (edit: rather than measure the cords themselves...). A difference in power, distortion and also output impedance were all measurable. The difference in power was not slight either! It turns out that like all other electronic parts, power cords obey Ohm’s Law and the voltage drop across them was the culprit. Yet how often have we seen dissent over power cords on this forum alone??
I hope you see where this goes- there are a lot of ’objectivists’ that claim a power cord can’t possibly make a difference- but I can now challenge them because I’ve made the measurements and they haven’t (which is a bit ironic...)!