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

Ones digital cable could be why some have negative comments about SS, and likely class D. I have owned quite a few AB SS amps, as well as class D (and a handful of tube amps & preamps. My current class D which I have owned for close to 2 years is the EVS1200 from Ric Schultz: Tweakaudio.com

Since I first got it I was using an optical cable. I wasn’t crazy about the sound and thought I needed to replace my Audio Alchemy DDP-1 + PS 5, but I don’t have that kind of $$$ sitting around, and so, I needed a plan B. About a month ago, I got the bug to try coax (FINALLY). Being budget minded, I bought 1.0m Pangea Premier SE ($49.95 from Audio Advisors) and started a thread. Someone recommended to get 1.5m, which I did, and though it was harmonically richer, I wasn’t sold on it.

I replaced the 1.5m Pangea Premier SE with the 1.5m Pangea XL, the presentation is much more intimate. I find my body grooving to the music: PRAT. Now, some 50 hours of play time later, I am blown away (especially for $150!). So far, every redbook CD I played I am much much closer to the actual recording: singers and instruments are extremely palpable and when recorded, bass, drums, and piano are very authoritative.

https://www.audioadvisor.com/prodinfo.asp?number=PGDCPXL&variation=1.5

I also like Pangea cables. I got the optical also a while back. I hear way more fidelity when hooking up using the coaxial input. I need to upgrade there next. 

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

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

Here's an interesting study.

Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect
https://b01fe120-8355-4a65-8abc-c8b51b6192cc.filesusr.com/ugd/d25f4f_a07d2fffb4244c4aa3341eb3c12e1e3...