So, IMO, the most musical and human sound is from a single ended triode amp or preamp (SET). Think the SET is the oldest still used audio amp circuit. Used in the first Bell telephone systems (WE). Funny, SS wants to sound more like tubes and multiple output tube amps want to sound more like SETs... sort of.
SETs are known for the warmth they have; that is caused by a predominate 2nd harmonic distortion. The ear assigns tonality to all forms of distortion; the 2nd is responsible for 'warmth', 'bloom' and the like. The 3rd and 4th contribute to this as well.
A good SS amp might sound very tube-like; as both tube and solid state become more neutral they will sound more and more alike. IMO/IME the issue that plagues SETs is that most people simply don't use them on speakers that are efficient enough. This is because the amp should *never* be driven past about 20% of full power, otherwise the higher ordered harmonics begin to appear. The ear uses these harmonics to sense sound pressure; since music has many transients this distortion initially appears on transients, causing the amp to sound very 'dynamic'. This is why many SETs get comments about how dynamic they are despite their low power. Its distortion masquerading as 'dynamics'. Whenever you see that its because the user was using a speaker of insufficient efficiency!