But you can't value your own perception over someone else's. There could be a lot of people that do hear the difference in capacitor values (I sure can when I change the caps in a guitar, why not someone else in an amp?). And there could be a lot of people that don't give a rat's ass about what you did to the amp, because they may use it in a totally different way than you, negating the change. None of us should presume to be an arbiter of what others can and can't perceive, or what will or will not work for them, because it comes off as you feeling your opinion is more important than anyone else's - saying that when YOU make it change it is for a big difference then minimizing any differences that occur when someone ELSE makes a change is bordering on arrogance, sorry.
My methodology is very different here, in my discussions with you, than in the real world and i think that's a distinction that's being overlooked herein.
All these years that i worked as a session player, i told nobody nothing of my own opinions. I LISTENED and focused on doing what i was told and that quality kept me steadily employed.
Now, when i am asked specifically whether a given mod will produce a tangible change, i will offer my opinion in that context.
I believe i have a responsibility to my students to tell them something other than "paper in oil is best," or all the other bull

that's been preache for decades, and in that context, i do interject my opinion.
I'll give you a real-world example.
A client recently asked me to change a ceramic disc capacitor - that measured .047uf - for a PIO that measured .047uf. I did what he asked and he was puzzled because it made no difference at all and i told him that it absolutely could not make a discernible difference from a scientific standpoint.
You cannot, in all honesty and candor, compare that to what
@syscokid did to the Marshall Origin. Its a completely different thing, regardless of perception, or whther or not you like the tonal change, the tonal change slaps you right upside the head, and even non-musicians have commented on the change, and it is that precise distinction that is being disregarded within the confines of this discussion.