What is your experience with the law of diminishing returns ?

Without any reference point, this is a tower of "Babel"; it's like asking the question; "How far is it from here to Chicago". Where is here? If we don't know that, what's the point of the question.

I suggested a reference point that I know is valid, and even if you disagree, I would hope that you at least know what it is; so far this is a totally meaningless conversation.

I don't understand the question asked, so if the OP could please elaborate a bit that would help.

If the question is about the direct correlation of performance plotted against price and the point where the performance curve begins to flatten against increased price, I stay away from that transition. I neither have the funds to spend in that region nor do I feel the need to waste valuable resources to gain such self-convincing, minor, improvements.

viridian: I hope they threw the book at you :)

When I first started upgrading, I could hear the difference.  However, I couldn't always tell if the upgrade was an improvement, just different.  Eventually I learned.

I hit diminishing returns when I couldn't hear a difference after an upgrade.  But there was still a  cumulative effect from multiple upgrades -- like I couldn't hear differences each time when upgrading amp, preamp, and cables, but after all three upgrades, I could hear the sound was better.

So I kept upgrading until I got to a level where my ears/brain had stopped learning and I really couldn't tell any more.