The only "real" answer is for you to try some of this testing for yourself. Asking a forum will get you no clearer understanding.
...there is no answer because nobody will be able to try all amps.
I don't think he's asking the "forum" in order to "sway" or form his own opinion.... He's just interested in what others have to say; give their opinions on the subject.
It should be OBVIOUS that NO one will ever get to listen to EVERY amplifier on the market..... However, someone may only ever audition/hear TWO or three amplifiers in their life time but still hear a noticeable difference between them! If that person never auditions another amp, they can still
'say' that there is a difference (in sound) between SS amplifiers! IOW - you don't NEED to 'hear' every amp ever built to answer that question!
I think what most are forgetting is that SOUND is interpreted differently by different people.
Example:- I was a DJ for many years and was quite successful at it! My younger Brother however, never could
"hone" his DJ skills enough to
"perform" in public venues. He couldn't
"align / blend" beats/measures well enough to be effective YET he literally spent day and night practicing. I, on the ther hand, never really practiced much at all.... It just
"came" to me naturally. When I tried to "coach" him, I found that there were
"sonic signatures" that were inaudible to him. I could hear them clearly but he could not! My point is.... SOME people have better (audible/sound) acuity than others! AND that's a FACT!
IMO.... SS amps do sonically/audibly differ! Maybe not to a large degree, but they do differ.
B-