Who tried Class D only to return to S/S or Tube

Firstly, let’s get a major misconception out of the way: class d amps are not digital, they are analogue.  And not all class d amps have square wave performance as shown above, though listening to square waves doesn't seem too common...Hard to place any real value in the opinions of those who do not even understand the basics of the technology or misrepresent the performance of high quality, state of the art class d.

Secondly, amps are part of a system. They don’t perform or sound the same in all systems. Some may be great in one system and not so great in another. This is true not only for class d but for class a, a/b, etc. Sweeping generalizations based on limited experience or use are worthless.

Thirdly, the objective performance of many class d amps is better than nearly anything any tube amp is capable of, and in the case of Hypex ncore, better than nearly any ss amp one can buy. Subjective performance can not be argued as it is a matter of individual taste. There are many many people who have dumped their ss or tube amps in favor of class d. Claiming the technology is "not there yet" is a bit behind the times and ignores the fact that not only is it "there", but it is replacing class a and a/b ss and tubes amps in large numbers.

Enjoy whatever works for you. No need to put down what others enjoy.

I think it comes down to the simple reality that audiophiles are in general a very insecure group. Many like to think that whatever components they have are "the best" and will go to great lengths to put down the choices of others in a senseless and futile effort to somehow prove the superiority of their choices, blind to the fact that there are no absolute "right" choices in a quest that is entirely subjective, and thus personal.

Most high-end audio manufacturers cater to this insecurity in a market that thrives on "mine is bigger, better, more expensive (thus sounds better) than yours"...

Class d seems to be the red haired foster child for those with deep insecurities, or perhaps, vested interests, as it gets kicked around all the time. Perhaps because it offers a level of performance to the masses at a previously unavailable low cost, taking away much of the snob appeal many of the insecure so value...For those without vested interests or insecurities, it has proven to be an exciting and fulfilling option for amplification. Excellent measured performance, high performance to cost ratio, small, light, energy efficient, plug and play without any finickiness, the list goes on and on. Never mind the fact that many have dumped their tubes and high dollar boutique ss for class d...No wonder people feel threatened!

Clearly, the reason there are so many different types of speakers, amps, dacs, etc., successful in the marketplace is obviously because tastes and priorities differ. There are many roads to audio paradise, none more valid than the next; we shouldn’t be so concerned and critical with the route others take but as fellow travelers, wish them well in their journey.

2nd generation is already here. Ableteck, Pascal and Hypex are all making 2nd generation class d amps that are competitive with nearly anything ss or tube based at less than ridiculous prices.

There is no issue with the switching frequency nor the filtering in these modules. None of these produce any audible distortion products at the tweeter. I have heard all three. They are all excellent and have been well reviewed.

I have answered your question already. Reread above...

Have you heard an Ncore, Pascal, or Abletech based amp? I have. They have all been reviewed very positively with no complaints about switching frequency artifacts. Perhaps future products will operate at high switching frequencies, but that is no panacea as high rates introduce other issues. Read Putzey’s papers on class d design. He addresses switching frequency. With the audio quality attained with these modules, your switching frequency concerns are a solution in search of a problem....

Mature or not, it has arrived, and is already making major inroads in the amp market. Many, as mentioned, have replaced their big name tube and ss amps with class d. It’s here, it’s thriving, and it can only get better, which is scary to think about...especially for those invested in tube and ss tech...

Some prefer tubes, some ss, and some class d. It is painfully obvious that tastes and preferences can and do differ so why people continue to debate and argue over the "superiority" of one topology over another is simply idiotic.