Devialet Expert isn't good in showing secondary harmonics?

[Confused]

I've been doing a bit of thinking (DANGER!!!!) about what an amplifier actually has to do, in terms of it's job of taking an input signal, and 'amplify' it, creating specific volts / amps to feed a speaker coil to accurately control the movement of a speaker cone, to reproduce that original signal as a sound wave.

If I think about a guitar string, I can easily envisage what it means for that string to vibrate with first or second harmonics, and how this produces a different sound. However, how does the second harmonic present a specific challenge for an amplifier, in that it would work well with the first harmonics of any frequency, but struggle with some second harmonics? Here I am stumped! Utterly stumped.

I quite liked Damon's tubey bloom theory, in that maybe the Devialet is very accurately not doing something. Something that some amplifiers might do that 'colours' the sound fractionally, but subjectively sounds pleasing.

As for Devialet amplifiers being good at first harmonics, but struggling with second harmonics? Well, I'll use a true audiophile phrase here; utter foo!

(it did get me thinking for a while though, but I'll stop now)