Turning this around a bit, searching for small improvements on an already excellent and balanced system is one side of the coin, but a small sonic defect can be like a stone in your shoe that just gets more and more irritating. I'm sure that's a path many of us have been on: initially a system sounds excellent, but then experience with it over time reveals small annoyances which take on larger proportions until the next upgrade, and the cycle starts again. Against that backdrop, small differences and diminishing returns become something else. Like a drop of urine in your glass of Scotch!