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

Really depends on the speaker in my experience. Went with the class A few esoteric 30 watts in my smaller room during a demo of a speaker I desired.  Made a deal for the speakers and demo amp.  Despite my current speaker 8 ohm 92 dB sensitivity the combo is awful.  Still waiting for speakers to arrive
From Scotland 

S’funny, one of the nicest class A amps I have heard is a positively antiquated JLH69. It can really sing with a pair of heritage Klipsch’s. There is something fundamentally ‘right’ about its sound that a lot of more modern amps fail to grasp.
AB can sound great too. All depends on the implementation.

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.

The class of operation has nothing to do with what load impedance the amp can drive. They simply aren't related, plain and simple.

I have a First Watt Sit-3. (Class A)
It does not get hot.
18 Watts can provoke ear-bleeds with Cornwall IV's.
Efficiency?
YES! ;-)

Hi,
I compared the sansui AU-777A and sugden A21, i preferred Sansui, and my best integrate amp is Sony ta-5650, really better than two amps.
The sound of the Sony is the same than pass first watt SIT (V-fet transistors), the new name is SIT.