The Future of Audio Amplification

You can mess up any amplifier operating class. The specific implementation is more important.
Class A implies better quality than D or inverse F, but that "class" system is not a value scale.
Class A sets the zero signal in the middle of the operating range, as to avoid the typical non-linearities at the extremes of the device's transfer curve. This was in started in the tube age. Many later semiconductor devices had poor linearity, which was "fixed" with gobs of feedback, and transistor power amplifier output stages almost exclusively have no gain, they just operate as voltage followers/current amplifiers. So linearity biasing is not the goal here, but avoiding ugly transitions when the voltage crosses the zero point. 
There would be more work getting a D amp to perform well, but of course as this thread has shown it is possible. The digitizer must be very good, operating at a high frequency and have good filters for the output. Higher frequencies will be easier to filter out and will have more resolution. 
The bit stream output from a DAC could be used to drive an output stage, perhaps skipping some time middle pieces. Change the power supply voltage and the gain changes. 
Obviously junk in the power supply will end up in your ears.

@kosst_amojan
The Berning TF-10 is a tube preamp with about 10 tubes in it. It draws about 60 watts; that's about the same as my laptop charger.

Panasonic came out with a new formula for electrolytic capacitors some years back that allowed them to be a lot smaller with good performance. Chinese copies of that part proved to be unreliable but due to their price found their way into a lot of consumer gear- laptops, chargers, that sort of thing. So I've become hesitant to blame electrolytics for failures generally speaking, until I know more about the actual part used. If its one of those knock-offs, its going to fail no matter what.

Funny, I haven't read anyone comment about having owned both class d and a-a/b. I'm very interested in what they think. This thread, as well as the entire audiogon forum, is populated with either/or, one or the other, with very strong advocates in both camps. 

Funny, I haven't read anyone comment about having owned both class d and a-a/b. I'm very interested in what they think. This thread, as well as the entire audiogon forum, is populated with either/or, one or the other, with very strong advocates in both camps.

I haven't been paying close attention to this thread, so perhaps someone has already responded in a similar way.

I've owned many amps that use differing underlying technology.  I'm including integrated amps in the lists below.

For class A/B I've owned the following brands - Rotel, Parasound, Krell, Lexicon, Marantz, and Emotiva.

For class D I've owned the following brands - Wyred 4 Sound, Peachtree, and Sunfire.

For tubed amps I've owned Rogue Audio and Audio Research.

I recently purchased a Heed Elixir integrated that uses what Heed calls "Transcap" technology. 

I have not owned any pure Class A amps.

I think they all have strengths and weaknesses and what really matters at the end of the day is how they sound.  A lot is going to depend on the way the designer understands and implementsed the technology and the level of the build quality and components. 

Out of all the amps I've listed, the ones that I have liked best (and still have) are the Rogue Audio M-180 tube monoblocks, the Wyred 4 Sound Class D ST-1000 MKII, the Audio Research tube VSi-55 integrated, and the Heed Elixir integrated.

It's hard to imagine the entire market going in one direction or another.  Designers may be more knowledgeable about a specific type of technology or prefer the way it sounds and so it seems logical there will continue to be diversity among design and implementation philosophies.

Vive la différence!