Decware and SET Low Power Tube Amps with Hi Efficency Speakers

@larryi .. as I understand it the efficiency is too low with both ProAc's and Harbeth's, thus a bad match for Decware's line. Harbeth, for example, state in their FAQ:

We have a social responsibility to our neighbours (and to our own ears) and we'd recommend 100W per channel or so for those occasions when the neighbours are out. But for normal use in a small room listening relatively closely to low-dynamic music, 20 or 30W can sound loud enough. A practical compromise would be an amplifier rated at around 50W/channel/8 ohms.

Perhaps this is the reason for the dull and lifeless sound you heard. The efficiency of my Omega's is 94.5, which is on the low side for a 2 wpc amp. For me, the SE84UFO is anything but lifeless.

wtf,

Yes, that might be the case.  However, other similarly low-powered tube amps, such as the Audio Note Oto and a tiny Synthesis amp sounded MUCH better with the same speakers.  I am merely cautioning a prospective buyer to not automatically accept rave endorsement of this particular brand (or any brand).  It is not that the raves are dishonest, it is often the case that the person is encountering tubes for the first time and is so captured by the sound that shortcomings are overlooked or the person is unaware that other tube gear will deliver that same kind of sound, but with even better performance.

Harbeth claims that its speakers must be used with high-powered amps, ideally solid state amps, but, I've heard them used with quite low-powered amps and they sound really good as long as they are not required to play at extremely high volume levels.  I heard the 40.2s played with a fantastic 10-12 watt amp and the sound was fantastic.   

I run a Decware Mini Torii 4 watt tube amp with 92db eff Ref 3A de Capos in 12 x20 room partially open on the long side so the speakers are 14 feet from me.  loud enough but not blasting, very realistic and detailed sound  feels like the npr announcers are in the room :)  and the music sounds great

have also use them with Klipsch Quartets-97.5 db  very different sound and gets loud, the Klipsch are now on a second system with a 2 watt Grommes SET/P amp

Both the Decware and the ZUs respond well to a little more power than most SETs can provide. A lot depends on the room- how lively, how large, how close you are to the speakers, and your own tastes.

One dealer of ours was using our MA-1s (140 watts) on the Decware speakers but overall I would regard that as unusual- I really think in most rooms that kind of power is way overkill. Here at the shop we ran our ZUs with our smaller amps which are 30 or 60 watts and the results were outstanding.

@larryi  .. fair enough, no one should just accept raving fan boys gushing about any gear. The OP did however ask about Decware's low-powered SET amps paired with high-efficiency speakers. Decware has been around for quite some time now and their amps have been well-reviewed with appropriate speakers. Neither their philosophy nor their products are everyone's cup of tea but they are well-built and have great value, certainly worth a 30-day trial for those wanting to go down this path. 

BTW, I've used supposed under-powered amps with a variety of very inefficient speakers with surprisingly good results. My Mark & Daniel Rubys with 82.5 sensitivity sounded great with a 25 wpc amp as long as I didn't push it too much. Same with my MMGs. As usual, it's system dependent and personal taste.