Hey, Folks,
For several happy years, I enjoyed the music making company of my Audio Note Kits "Kit 1" 300 B SET amplifier, which I built with my own two hands (loved the experience). As documented on my blog, here, I eventually learned that although sensitivity ratings (the stuff you see quoted in decibels in manufacturer's literature) are certainly important in finding a good match for a low powered, single ended amplifier, it doesn't tell the whole story. I thought that my Spatial M3 Turbo S speakers sounded splendid with that single ended amp, and they did… until I happened to hear the same speakers with a high-powered, solid-state amp that I had borrowed and that seemed to make everything I like about the Spatial's a lot better. When I spoke with Clayton Shaw of Spatial to ask him why, he explained that sensitivity is part of the story (and an important part, since ideally you want a SET amplifier to be operating within its "1st watt” for lowest distortion), but you also have to take into account the impedance curve of the speaker – how difficult or easy a load is it for the amplifier to drive properly? And in that regard, the standard M3 Turbo S was not going to be a particularly great match for a SET amp.
By the way, I ran my Reference 3A De Capo monitors (which I loved) with that 300 B amp for quite a while. It sounded lovely, but it turns out that the sensitivity ratings given by the manufacturer are somewhat optimistic. It's not a slam on the manufacturer or the speaker – both are great – but there doesn't seem to be any standard way of determining sensitivity, and the question is always, across what part of the frequency spectrum is the speaker that sensitive?
Anyway, let me toss out a somewhat out-of-the-box suggestion. You might take a look at the very well reviewed Fritz Speakers Carbon 7's. Although the sensitivity ratings of Fritz's monitors are not at first glance especially high, their impedance curve tends to be nice and flat and an easy amp load due, in part, to the series crossovers that Fritz uses. Plus, Fritz is a sweetheart to deal with. Anyway, here is my review of the Carbon 7 SE speaker paired with my old 300 B amp. Enjoy.