The Future of Audio Amplification

So funny and incorrect.  All class D modules produced by the major companies 10 years ago are still available.  Example:  Here is the module that was sold in 2007 being sold now through Parts Express....
https://www.parts-express.com/icepower-1000asp-class-d-audio-amplifier-with-power-supply-module-1-x-...

But why would you want to replace your module on your 10 year old $2000 amp when you can buy a brand new better sounding stereo amp for a little over $1000 delivered?

There are guys buying super expensive class A amps right now that will be turning them around to get the latest new one in a year or so and lose $10,000 or more in the process.  Some of the best sounding newest class D amps are so good and so cheap that you could just throw them away (or sell or give to your kids or use in secondary system, etc.) in a few years when a better one comes out.  Never heard anyone cursing their inexpensive class D amp when it is no longer the latest thing.  I think the rich guys do more cursing and also more straining.....lifting those beast of amps!  I read a lot of reviews of the latest class a and a/b amps and it looks like the latest ones (and also getting more expensive every year as well) are really way better than those old amps that are 10 years old.  All classes of amps are way better today than ever.  Lets all sing along:  "Who wants yesterdays papers?.....Who wants yesterdays amps?....nobody in the world"

There are many class D amps out there.....some sound eh....some sound middling, some sound very good and some sound really great.  Just like anything, you need to do your research and buy from someone who gives a trial period......but the same is true with any class of amp.

 newest class D amps are so good and so cheap that you could just throw them away

That's just great, depends just how well off you are. Try saying this to an owner who Class-D has just smoked it, as see what you get back in return.
Also you sell them, so you and are definitely not impartial.

newest class D amps are so good and so cheap that you could just throw them away

What a wonderful throwaway society we now live in when we can even consider that statement as not only being relevant but likely the truth.
Very sad reflection of todays mindset and the times.

No one has mentioned GaN class D yet. Seems to be a game changer

If GaN acts like a V-Fet or a SIT, then they might be on to something.

The non linear gain curve of a modern transistor will generate odd order harmonics, which is where the problem in audio lies.

A SIT or V-Fet, produces predominantly even order harmonics, which is tied to possessing what is principally a linear gain curve. More akin to a tube. A triode tube, specifically. This is critical. Big time critical.

To test this theory, one has to make a modern Class D amp with a modern V-fet, which means Tokin devices. Which are available on ebay as the last of their kind. These are high current high voltage devices. (the Tokin versions)

The future of audio is very likely V-Fet/ SIT.

Class D, as it stands, produces what is predominantly odd order harmonic hash, which is filtered.

The shape of that odd ordered hash is mistaken for detail, as the components of it (mix of odd ordered harmonics) meander around (shift and change) in the presented mix.

I heard it for what it was the first time I head a class D amp, and it is there in all of them. Garish, faulted right to the emergent core, unlistenable. For me, that is....as I heard it and recognized it...that it is totally against the aim of audio technology, in my view, hearing and understanding. To take the worst and unwanted part of what solid state devices do and make it the ENTIRE waveform. Jebus.

This is mostly testable in a finished item...as Sony did it right and made a class D amp back in the day, with SIT or V-Fets as the output devices.

Not as much of a modern refinement as the current crop of Class D amps, but the build/design clues for working with SIT devices are all there in a pre-existing finished item.

Interestingly enough, modern V-Fets/SITs are designed to be high frequency high powered choppers of the like that are required for Class D design.

We had it in hand, we were on our way... but mosfets killed the audio star....