Well... I'm a bit surprised... I got the Hegel H590 to drive my 30.1's and 40.2's, because when I first tried them with the AR Ref 5SE and Ref 150SE tube amps, the Harbeths seemed to lack clarity and dynamics, and had somewhat boomy bass. The H590 cleared all of that up, and really made the Harbeths sound like they do in the YouTube videos - which is exceptional!
However, I recently decided to try the AR amps again with both sets of Harbeths and was surprised that after some burn in, they began to excel with the AR amps - especially when using the 16 ohm speaker taps. Amazing actually with a bit more air and bloom than with the H590 - much as you would expect from a Class A tube set up. And the bass is well controlled, with texture. Pretty amazing, actually!
I almost think I like their sound better with the AR tube amps, than with the H590. Will have to switch back and forth a bit and see... but... right now... I'm truly amazed at the sound they're producing with the tube amps!