Please help me understand

Danoroo,

Music is just much more complex than any test while warm or bright is just different types of distortion. Why do you think amps should sound the same? What is to my liking is not necessarily your cup of tea. I like neutral sound while you may prefer warm sound. There is also synergy with the speakers and the rest of the system including listening room. In addition, since there is no perfect amp, some amps are better than others for given type of music. It would be nice to know ahead, performing some type of complex test, but as it stands now even known types of distortions (like TIM responsible for brightness) are not listed, being often too cumbersome to measure.

"some of them aren't doing their job very well"

Yes some of them are poor, but often you face compromise for the type of music you like - unless you have a lot of money (there are amps up to $1,000,000) and it can still have poor synergy with your system. Trust your ears and quit reading technical specifications because often amps with the best specs have the worst sound (and there are technical reasons for that).

"Just food for thought, your family pet 'hears' more"

Man: 20Hz-20kHz
Dog: 40Hz-40kHz

Same number of octaves (10)

"Dogs don't listen to loud rock music"

Sure they do, they listen to owners loud music. They also bark - a very loud noise.

Everybody looses hearing with age - man or a dog. Prolonged loud noise can only make it worse.

"quite possible that the human ear might be on some level analyzing things that are either yet to be identified and labeled"

Transient Intermodulation, unknown until 70s, comes to mind. Early SS amps sounded very bright because of overuse of negative feedback but designers claimed that it has to sound better than tube gear since THD and IMD are way lower. TIM is very seldom tested since there is no established test method. Even the simpliest specifications like THD don't show the full picture since it is different at different frequencies and power levels.

As for being able to repeat particular amp, I'm afraid that no matter what you do SS won't sound like tube gear simply because of completely different interaction with the speaker. SS amps are voltage sources while tube amps are power sources. You can attempt to emulate sound of particular amp/speaker combination in DSP processing (many guitar amps do it) but results are rather poor. Nobody, so far, was able to make electric piano sound like real one - not even close. We are pretty much on the level of trying to understand why wires have particular sound (silver vs. copper etc.). Even same tubes made by different manufacturers sound different. It is still mix of science and art.