I am pleased that you tried something that you were sceptical of and were rewarded for your curiosity. As Detlof said, the proof lies in long term listening. Perhaps your new acquisition will add to your listening pleasure and encourage you to do additional testing.
Your concerns about diminishing returns are well founded. I must add though that the least expensive system that delivers sound is the best value. From there on, each must decide just how far to push the envelope, and how to value each incremental gain. As with all things in life, the closer to state of the art (or perfection) , the more expensive it becomes.