I have been quite impressed with the Horning systems set up by High Water at several shows. They were driven by top of the line Tron amps and Thoress amplification. This is a very dynamic, and immediate sounding system but Horning manages to tame the midrange peakiness I would have otherwise expected from the Lowther-based midrange driver. But, I would guess that that kind of midrange speed and detail makes this a VERY picky system when it comes to amplification.
I agree with Charles1dad that ease of driving is particularly important. I think it is much more important to matching with tube gear than efficiency. I heard low-powered amps on a pair of original 15 ohm Rogers 3/5A speakers sound wonderful in a quite large listening room. Those are something like 83 db/w efficient, but at 15 ohms nominal impedance, very easy to drive. A lot of fairly efficient speakers, like Wilson speakers, seem to be particularly challenging to lower powered tube gear because they have a load characteristic that is not suited to such amps.
I agree with Charles1dad that ease of driving is particularly important. I think it is much more important to matching with tube gear than efficiency. I heard low-powered amps on a pair of original 15 ohm Rogers 3/5A speakers sound wonderful in a quite large listening room. Those are something like 83 db/w efficient, but at 15 ohms nominal impedance, very easy to drive. A lot of fairly efficient speakers, like Wilson speakers, seem to be particularly challenging to lower powered tube gear because they have a load characteristic that is not suited to such amps.