SET amps ?

You might be surprised at how far 8 watts of SET power can take you. The DeCapo's are very good and an easy load to drive. Depending on your room size and how loud you like to listen, 8 watts could easily work. A lot will depend on the quality of the output transformers and it's impedance. However, as a case in point our 300B SET (12 watts) was used with Fritzspeaker Carbon 7 monitors at 87dB and 6 ohms in a 13 x 18 room and we could not clip the amp. We were getting SPLs over 90dB quite easily. If anything the room itself prevented us from really cranking it up.

Tubegroover,
Clio09 makes a good point, it really depends on your speaker's ease of drive (not just the sensitivity rating) room, music genre and listening levels.
His result with a 10 watt amp is similar to mine with an 8 watt amp.
I listen to predominantly jazz and big band and sound envelops my room (14×25×8 feet). When I do play classical, usually small-moderate scale it is really compelling and engrossing . Large scale orchestral music is quite good with my 94 db 14 ohm speakers. I won't claim that this is the ultimate set up for large scale orchestra but my point is it does provide a satisfying musical experience. The presentation is very resolved, delineated and lively emotionally.

I'd say the Coincident, Wavelength 300b (several versions available) and Clio09's amp would be worth a listen. Tubegroover, a 845 SET amp may be ideal if your music is mostly larger scale classical fare and high sound volume.
Charles, .

Goldeneraguy,
Thanks for the invitation to hear your system. At RMAF 2011 I heard the Tron electronics driving a horn speaker in the High Water Audio room and it was one the very best rooms I heard there.

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.

Larryi,
I believe that the Horning is successful using the Lowther as a wide band
midrange driver rather than stretching it to the very upper frequencies as a
"full range" driver (they also wisely removed the whizzer cone).
Larry I truly believe that high impedance speaker loads are absolutely
advantageous for SET amps and lower power tube amps in general.

It often seems as though my amplifier is just coasting driving my 14 ohm
speakers. I definitely can relate to your example of the Rogers 3/5A
characteristics with low powered tube amplifiers.
Charles,