Is there a point of diminished returns with amps and Harbeth 30.1s?


I’m currently using Herron M1As with my 30.1s and I’ve upgraded the rest of my system (Aries/Fatboy/SUT/DL103r and Lamm pre and phono) and each upgrade has been VERY satisfying. So is it going to be worth spending $5000 or so on the used market to upgrade the Herrons? Any thoughts as to whether I’ve reached the apex of amp/speaker performace for the M30.1s?
dhcod
 A straight wire with gain as Quad's Peter Walker once said. Didn't he also claim that he didn't need to listen to his amps? The measurements alone told him everything he needed to know.
This is a view that most amplifier designers disagree with, not to mention the vast majority of audiophiles. 

Measurements do not tell the whole story.
@whipsaw

i think we are better off not wasting our breath

published studies, measurements, ’verification’

sheesh... missing the point of what this pursuit is about it seems

enjoy the tunes, and onwards...
CD318, perhaps start a new thread on blind listening test with level matched amps if you are interested? You may attract more interest from people who are keen on the subject instead of posting it here on this thread.