What are the advantages to a Class A amp & what are the trade offs?

Not to be argumentative, but don’t you think that the interface between class AB amps running in class A going into class B is not rocket science and has been perfected years ago? 

Grandstanding a bit, I would guess the majority of great SS amps are class AB, based on sales.  Just an assumption on my part.

Well, I have had some quite powerful small Class A/B amps which deliver 2-3X their rated power. Not only that, but they are about 3X to 5X as powerful on a wattage rated basis as many solid state amps.
The earliest amps to sound super dynamic is the McIntosh MC30s. Next are my highly modified Dynaco’s which can deliver huge and clean bass dynamics into low impedance loads. Lastly, my custom built Altec transformer based 130 watt amps which could drive anything a 500 watt solid state amp can. Maybe my Class A/B amps aren’t as refined in the mids as the best Class A tube amps I’ve heard, but I can put my hand on my big amps transformers hours after being played hard while I could burn my hand in 15 minutes anywhere on the chassis of an EAR 890 70 watt Class A amp which can’t handle low impedances.

Kosst, I mentioned that "the interface between class AB amps running in class A going into class B is not rocket science and was perfected years ago" and  also that while I was "Grandstanding a bit, I would guess the majority of great SS amps are class AB, based on sales. Just an assumption on my part."

You responded that class AB amps are akin to Kia's.  Youe clear meaning being they are cheaply build and inexpensive.  You chose to not acknowledge that I specifically mentioned that sonic problems due to the amps going from class A to class B are non existent and that I referred to great SS amps, not Kias level amps.

I'm just saying