I am a fan of Harbeth: they are the only dynamic speakers that I have heard that are almost as transparent and invisible as Quad electrostats. My main system has Quad 2805 electrostats (plus a 400 watt powered sub) driven by a refurbished 2x140 watt Quad 606-2. My earlier refurbished 2x45 watt Quad 303 was clearly not powerful enough in the quite large room, and sounded strained. The 606-2 sounds the same as the 303 at low levels, but is more dynamic and cleaner at higher levels. I may even opt for a pair of 2x260 watt Quad QMP monoblocks as my next upgrade.
My desktop system uses Harbeth P3ESR speakers, driven by a refurbished Quad 405-2, and I think that is about right for these inefficient speakers in a small/medium size room. It was Harbeth’s Alan Shaw himself who persuaded me that you need power, and the more the better. See here for a thread on the Harbeth User Group, with quite a few contributions by Alan Shaw himself, who, I think, would know best what his speakers like:
http://www.harbeth.co.uk/usergroup/forum/the-science-of-audio/amplifier-matching-mismatching-and-cli...I know there are good valve amplifier designs, but with many their for me fatal flaw is their load dependent frequency response, and that is why I would never contemplate them. There are many Stereophile tests that show these deviations in embarrassing clarity. Their distortion figures are also a lot higher, so what do I get in return for more money, more hassle, less energy efficiency and a fequency response that sometimes looks as if an equalizer has been at work to produce that glowing warm and/or airy sound? An amplifier with a frequency response that has big and audible peaks and dips is not a straight wire with gain. Everybody is free to want their own tone control system, but for me neutrality is what I want.