I am still wrestling with what WOULD create a night and day difference between competent amps. The blind shootout article could not identify consistent differences with music content. I recall several years ago hearing a big difference between my old Proton amp and my replacement Bryston. I also have “aural memory” of differences between my NAD C272 and the Bryston, but that was at least 10 years ago.
I’ll soon have 3 amps in the house again, so I’ll need to experiment. I probably won’t be able to do a blind comparison, but I’m curious enough to give it a shot. Hopefully, that will keep me busy enough to discourage me from dropping three grand on an AHB2 just to satisfy “curiosity” of how it might be better. I really don’t need another amp.
As far back as 20+ years ago there was an article written by a well-regarded engineer who basically said all competently designed amps (operating within their respective power and impedance envelopes) sound identical. It was IIRC in reference to his review at the time of the then quite new Audiolab 8000A... which I subsequently bought. His article created quite a storm amongst the snake oil peddlers especially. Funny that ;-)
From my own experiences at the time, I was upgrading from a Mission (as it was then) Cyrus 1, to one of a Cyrus 2, Naim Nait or the Audiolab. I spent an entire evening playing different tracks over and over and over again across the 3 amps. I think I could *just* detect a difference between them, but certainly not to the extent that any one sounded better than the others... to my ears at least. It came down to which one I liked best, and the idea that the Audiolab measured superbly - and had useful things like tone controls - was what swung it.
When I think that these were pretty low end amps in the scheme of things, and yet even at that level the differences were miniscule. I can only imagine that the difference in more modern amps costing 5x or 10x as must are smaller still.
That said, I have just bought a new NAD M33. For me, it's got to the point where usability, looks, features etc are at least as important - if not more important - than sound quality.
Of course if you feel the need to put stands under your speaker cables <falls off chair laughing> and buy a £150 mains lead then this will likely fall on deaf ears. No pun intended.