Why would anyone want class AB amp when class A always sounds better ?

Hi audio2design, go and pick up your Nobel.

You have designed an amplifier that is 100% efficient.
Not possible.

Although Class D is the first amplifier topology that theoretically offers completely linear operation with 0% distortion and no power loss at 100% power efficiency, the commercialization of Class D audio amplifiers had to wait until the ‘90s when silicon (Si) MOSFETs with sufficiently good device parameters became widely available.

https://www.powerelectronicsnews.com/opening-up-the-next-chapter-of-class-d-audio-amplifier-performa...

I saw theoretical max in the post. 

Since this is all subjective I wouldn't trade classD for classA  as long as each amp were designed properly and were used within their parameters. 

Just buy whatever sounds best to you..  Glad we have choices..
I will stick with Class A amps as they provide the best sound to my ears. I agree with @atmasphere , The topology is simpler, but requires a better PS and ways to manage heat. Those who buy based on efficiency alone are missing out..

I might be off here, but class A amps don’t drive lower impedance speakers very well either. Most class A amps aren’t stable into 2 ohm loads. Krell being one Of the exceptions.

I might be off here, but class A amps don’t drive lower impedance speakers very well either. Most class A amps aren’t stable into 2 ohm loads. Krell being one Of the exceptions.

Sorry your off, one word for both, no.

Cheers George