equating class A to class AB SS amps?

An amplifier is a tool to drive your speakers, select them first and the select an appropriate one that you like the sound of on THAT speaker. There are many factors involved, ghostrider has pointed several of them out. Generalizations about the qualities of Class A, Class B, Tubes etc. are less important than the qualities of a particular amp and how well it matches your speaker.

Big watts.. little tiny watts. Tubes have BIG watts... Class A amps usually have BIG watts because they have big power supplies..
Cheap class AB amps have little tiny watts, unless they are BIG, really BIG (and expensive).. and can double the wattage with halving the impedence. (Think Bryston 28B-SST*)
But really a Watt is a Watt. (though some small amps cheat and claim they have more: that is the 'little' watt side of the story.
Really a 50 watt amp only puts out 50 watts into 8 ohms, and a 200 watt amp puts out 200 watts into 8 ohms. BUT!! that 50 watt amp may put out 100 watts into 4 ohms and 200 watts into 2 ohms.. (a few such heroic amps can do 400 watts into 1 ohm) but the 200 watt into 8 ohm amp may only put out 250 watts into 4 ohms and actually fizzle to less than 100 watts into 2 ohms, and explode (blow the fuses) when it sees a 1 ohm load.
This is only to confuse you as the power handling ind low imepdence loads has NOTHING to do with class "A" or class AB
However it all fits into the big picture of how power amps are rated.

The other point is that many AB amps operate in class A until a certain wattage is reached, then go AB.

I used to have a 75 watt (into 8 ohms) class A amp that was beautiful to listen to.

Excellent answers, I always wondered about this too.

Thanks.

I owned an Aleph 30 (Class A) amp rated at 30 glorious watts per channel. Based on the different amps I have owned previously and a direct comparison to them, it had no more power than just a 30 watt per channel AB solid state amp.