equating class A to class AB SS amps?

Mark - When you listen to 200W peaks your class AB amp really delivers to speakers on average only few percent of peak power. It is because music is not always at the peak and half as loud means 1/10 of power. In addition there are gaps (unless you listen to sinewaves). Nobody sane would design power supply in 2x200W amp for 800W required (50% efficiency at best). Typical amp can deliver full power at limited period of time (like 1 minute) before thermal protection kicks in. There is no need to design large heatsinks for the same reason - otherwise they would have to be the same size as in class A amps.

Class A is extremely wasteful but has one big advantage - is more linear before negative feedback is applied. At the end (with feedback) both class A and class AB might have the same linearity but class AB required 20x more gain (before feedback) to achieve this. This huge gain (in order of 4000) in connection with limited response of the amp (limited slew rate) is causing late feedback correction. In time domain it shows as small overshoots of pulses and in frequency domain it shows as enhanced higher order odd harmonics (bright sound). This is called TIM (Transient Intermodulation Distortion) and was unknown until 70's. There are great class AB amps where designer minimized the problem and also some bad class A amplifiers. You have to listen. My general intuition is that better specifications mean worst sound (achieved by deeper feedback). Same with power - what is on the paper is useless. The only usefull parameter you can find there is weight (some correlation with power).

I noticed now "Many thanks for all the helpful replies! Now I am less confused"

Mark, I hope you don't feel more confused after my post (I tend to complicate things).

One other thought here is this... listening levels.

Listening levels are achieved only by the input of power to the speakers... ergo, watts. Class A watts, Class D watts or Class A/B watts... it'll take a certain amount of them to produce a certain SPL.

AS often as I've come over this issue, I continually forget the where abouts of the conversion chart online.

The amount of watts needed to produce the level you desire at times going into your speakers is quite important! An insufficient amount can put them in harms way either immediately or over some period of time if they are in fact being under driven, or starved for power, when trying to achieve the levels you wish now and then.

80% of the music is made in the first 20 watts.

But if the Verity's aren't very eff, or have some severe impedance drops with some freqs, more power is surely going to be needed than those first 20 watts.

I'm no paint peeling listener myself usually. 85-90% of the time I'm under 90db SPL. But there are those times one may wish to twirl the fun knob up.

Don't risk downtime or addded expense by runnnig with insufficient power.

Just a thought no one had brought up yet.

Have fun.

Just an after thought, AB also runs a lot cooler than class A amps.

In general, I love tube amps. I know this is a generalisation, but the solid state amps I have found listenable to, were nearly all Class A, the Aleph 3 being the best. I would love to hear the new integrated based on the XA30, I expect that will be quite special.
Otherwise, I found an edge, lack of musicality, harshness, call it what you will, to class A/B, SS amps. The only exception was the Lavardin IT, which was very nice indeed.