Which valve amp? None. Harbeth speakers prefer solid state. Hegel, Naim, Benchmark, Belles, etc.
If the bass works well in your room, then for me, that makes the amp choice much easier...many valve amps are not at their best doing beep bass slam!
I think the Americans do specialise in big power valve amps, and although I stand by my suggestion of the Luxman, if Mcintosh are in reach they would be worth a listen. I'm a little with alan S on this subject. The harbeths are not amp fussy as such. If they work in your room that's most of the battle, but they are at their best with a decent amount of power behind them. Ergo, something american, valvey and large would be a almost certain perfect choice. I'd certainly support the EAR suggestions too. Isn't that a good start? Forums do tend to contain people wholike to express opinions...just like you
@EPear The super tweeter doesn't sound bright because its frequency range is too tiny. You get a bit more air, thats all.
I am using Audio Physic Sitara 25 speakers you had AP's and used a Unison Research S6, which AP's?I have owned several Harbeth speakers, including the SHL5 (not plus).
I've also owned the following tube amps during the time I had the SHL5:
Unison Research S6 mkI
Jadis Orchestra Reference mkII
Icon Audio ST40mkII
Mystere ia11
Like Tony, I too am of the opinion that the SHL5 needs a bit of power to make them really open up. When fed with a decent amount of power and quality current, they go from good to very good.
Of the above amps, my joint favourites were Jadis and Mystere, followed by the Unison and last the Icon Audio.
I tube rolled a bit as well. The best combinations to my ears were Tung Sol 6SN7 and either Svetlana Winged C EL34 or JJ Premium KT77. I also liked the Groove Tubes EL34.
The Svetlana Winged C had a smoother, more velvety sound which I liked for acoustic music, especially female vocals and strings. For light rock (e.g. Fleetwood Mac, Supertramp, Dire Straits), the KT77 gave a punchier and faster sound with tighter bass compared to the Winged C.
For value for money, the Mystere wins the contest. At around £2000 it is very close to the more expensive Jadis. I liked the Unison S6, but did not think it was a good match for the Harbeth. I bought it at a time when I had some Audio Physic speakers and the S6 was a very good match with them, but not so good with the Harbeth.
I used some Eastern Electric (Mini Max) pre and power with my old P3s. Only 8 watts but the sound to my ears was superb.After greatly enjoying my Harbeth SHL5 with a 200 watt Lyngdorf SDA2175 power amp for a few month, I'm now listening to them with an Eastern Electric M520 valve amp, running its EL34s in pentode mode with -6dB negative feedback, only about 20 watts but lovely big 3D sounstage, and good weighty-but-not-soggy bass. I got the Eastern Electric for a good price off ebay so may go further with valves.