I’m also worried about how much of the harmonics in the music is LOST by the amp?

Not that I agree with a lot of stuff he says, I do with this one
https://www.psaudio.com/askpaulvideo/above-the-limits-of-human-hearing/

Cheers George

The fine detail and harmonics is normally lost in the speaker

Can also be lost in the type of amp used, when phase shift happens to the 2nd 3rd 4th harmonic structure of the fundamental, mids and highs notes above in this case Class-D >1khz.
As can be seen (red trace) there is 75 degrees!!!!!!! of phase shift at 10khz cause by the switching noise "output filter" in this Class-D amp, and still 40degrees!!!! at 1.5khz. https://ibb.co/cCL1M8k
Most of the magnitude of this phase shift can be remedied by, as Technics did with the SE-R1 to move the switching frequency (and it’s output filter) from 600-700khz to 3 x higher, 1.5mhz instead, and so the phase shift would also be moved 3 x higher up the frequency response scale far more out of the audio band more like good linear amps are.

And the reason why so many linear hiend amps sound so much more natural in the upper mids/highs because as they don’t have these sort of phase shifts well down! into the audio band. As they aren’t trying to "filter out" "Class-D switching frequencies" on their outputs, and their frequency responses go out to more than 100khz with hardly any of this sort of harmonic structure distorting phase shift down into the audio band.

Cheers George