What a marvelous (Delayed 😊) outcome for you. Very interesting and glad you shared this experience. I’m not at all surprised that the higher level/tier amplifier has made such an improvement. I happen to be one of those who believe strongly that amplifiers most definitely matter.
No doubt that your latest amplifier has better transformers/power supply/parts overall. It simply matters a lot. Your speakers are of such high quality that they will easily reveal any differences among amplifiers. Yours is a very good example of patience and diligence paying off in the end.
Charles