"I'm a believer"

I spend three times as much time being entertained on my $5000 “B” system than my $50,000 “A” system. 

In that case, perhaps you could swap the labels 

if you can get great sound from cheap speakers and good amp, then perhaps amp will have more diminishing return and be the boss. 

Rule of diminishing return, after all, isn't the only factor of the audio hobby.

Rule of achieving certain goal can sometimes break any other rule you can think of.

IMHO and years of investing, listening etc as mentioned by the OP. I think that speakers are the final destination of delivery to our ears for every dollar spent to achieve that utopia we all seek. But I think also we must agree that the speaker is the single most affected or influenced by the environment of the room in which they are placed. Room dimensions, furniture, occupancy of the room, wall hangings, open or closed door and the list goes on and on. All these with even the most minute of change are factors in what we hear. I too have heard speakers that alone double my investment in my whole system, and walked away thinking ‘what am I not getting’ for that kind of money. And others times I hear speakers that I would think of as small room system speakers and thought ‘why in the heck did I spend what I spent’ . So we have to eventually, well me anyway, just say this is my system and I will make the best of it and put on your favorite record and relax and enjoy the music and relive the pleasure it has brought you through the years.

Again my opinion and mental island of refuge for sanity’s sake

+1 to the comments by @theo about the room.

Speakers interface with the amplifier and the room. Both interfaces must be compatible.

With most speakers and short speaker cables and most solid-state amps, pairing with amplification is not a big problem. Still, amps are voiced a bit differently, and one wouldn’t want a bright amp with a bright speaker. When using tube amps, system synergy becomes more important because of their high output impedance.

As to the other interface, room acoustics are always important. Cheaper speakers in a good room will usually sound better than more costly speakers in a poor room. These differences are huge, and what can be achieved by improving room acoustics is far more important than swapping cables, DACs, or in most cases, amplifiers.

I may not want to know the answer, but why one sock?