Solid state design options...

How about the Belles 350A which is almost a purely class "B" design. It has a ultra high damping factor. Give one a listen if you get the chance or check out the review on Sounstage.com
Also, in the above discussion, a goodly number of amps use a cap to block DC on the input. This, to me, imparts a slight change in the sound for the worse. It seems input blocking caps have been substituted for DC servos (I know it's cheaper to do.) Also, as stated above, many amps go just a few watts into class A then crossover. With this, waveform distortions can occur. The positive and negative half cycles don't match up.
What i'm saying here is alot can happen to influence the sound of an amp besides the above listed things.
Why do people love tube amps---most of them stink on the test bench in any of these parameters. Most tube amps have a damping factor of around 20 or less! Could it be we like the "Distortions" a tube amp produces? (they sure test like crap!)

All the discussion points to one thing. Trade-offs for the typical audiophile amps. They were all optimized for a few particular things but not everything and they can't be due to cost consideration.

It's possible to design and build a 1000W/ch amp class A, balanced, zero-global feedback, balanced and high current delivery, but it will probably cost a quarter of a million dollars per channel and the size of a sofa.

So all these compromises designer made will basically force the marketing to emphasize specific strength which usually make all these terms unimportant and impossible to compare one on one.

If you are amp buyer, don't take these terms too seriously. If you are an amp designer, that's a complete different story.

BTW, if you can't tell yet, I am by training an eletrical engineer.

I am very picky. I own Krell.
I have no idea about any of these designs as they relate to any of the Krell amps that I now own or have owned in the past.

Buy a good amp from a good company.
Actually I bought great amps from a great company.

Just my 2 cents.

Richard

1, 4 and 5 are bare minimums for a nice amp. 2 is cool if you can balance the entire signal chain. 3 is nice if you can live with the heat and the electric bill. If you dig spec'ing out solid-state amps, compare the number of output devices/channel and the amounts of distortion and noise. After a while you'll get a feel for where the corners were cut.

I usually take a peek at the slew rate. To me it says something about how careful the amp design is; if the amp sounds good to boot, then somebody did his homework. Higher is better but if the topology is sloppy, a high SR can mean instablity, distortion, and noise - especially with more output devices. IMO, this parameter gives the amp its speed (pace), adds to the illusion of realism by presenting transients closer to real time, and presents quieter silences. Of course, it doesn't pull everything together - there are many other factors (I wouldn't call them "marketing gimmicks", they are just specs, which show performance, which in turn only hints at the sound).