Herron M1-1A monobocks, what do you think?

I will swim against the current here and say I was underwhelmed.
Herron Audio is well-respected by all and enjoyed by many but, in my system, while the M1A amps sounded nice, clean, and pure, they did not display the same level of dynamics, impact and depth as the better amps I have owned.

Hi Bpoletti, I went back through pics of stuff I have sold and found I was mistaken in my earlier post. The Herron amps I owned were the M1 monos, not his latest M1A monos currently shown on the Herron website. I could find no info by Herron of a model M1-1A that was asked about on this thread so I assumed the OP meant the current M1A model.
As with his earlier M150 amps and current M1A amps, the M1 amps output 150wpc into 8 ohms and 275wpc into 4 ohms, with an unusually high input impedance of 220K ohms. I could not find any info on what was changed between the models M1 and M1A, although the 2011 Positive Feedback Online review referenced on the current M1A page of Herron's website is for the M1s that I owned so I assume the changes were evolutionary and not revolutionary.