Thanks for all your responses.
I went ahead and bought a Hegel H300 to go with my Harbeth P3's. Even though the Harbeth's are amp friendly, I am impressed with the upgrade in sound that comes from the increase in power.
The Hegel is both refined and dynamic. The smooth, tube-like richness of tone is intoxicating. I may have found my forever amp.
Now maybe I should audition the Harbeth 30.1......