Efficient, affordable speakers for SETs?

I agree with the high efficiency speakers.  I have a custom pair for my family room setup, which are driven by a 45/46 SET amp.  (Both are designed by Don Allen.)

The speakers use Eminence 15" coaxial drivers.

@rickraymond59 couldn't agree with you more!

I toally back up rickraymond59. My Zu Soul Superflys really sing when running off a SET amp
As do my Klipschorns.
As do my KEF Transmission Lines but you’ll struggle to find a pair of them as they were home built.
I would think any Zu would work fine as would any vintage Klipsch.

I had some experience with PHY drivers. The Ocellia speaker uses them and is very sensitive but not dynamic enough. Audio Note UK are an industry standard for decades but their output is also somewhat limited. The Ocellia and AN seem good for classical and Jazz.

@mglik FWIW its impossible to design any hifi audio product to favor a certain genre of music. We did have a pair of Ocellias here and I personally found them to be way too colored due to cabinet resonance. However the drivers themselves are quite good and as dynamic as any high efficiency 'full range' drivers.

There’s also a somewhat hidden corollary, here, which is that I ended up multiplying my error by saddling a low power / high output impedance amplifier with a 12” or 15” woofer.

@jim_hodgson If the speaker is designed to work with amps of high output impedance then no worries driving larger speaker cones at all. IMO that is one of the bigger myths around SETs and large cone speakers. Our amplifiers have similar output impedance to SETs, and have no worries with the dual 15" woofers in the Classic Audio Loudspeakers (which are 97dB). The impedance usually plays a far bigger role!

If you're so dead set on running an SET amp, then the only real answer is the K-horn.

I would regard this as inaccurate to say the least. JBL made many speakers, amongst them the Hartsfield, which have similar efficiency. The Hartsfields were designed for corner operation (although the reproductions made by Classic Audio Loudspeakers seem to work quite well when not placed in corners). When I was in college I had a set of Altec corner horns; there are also things like the AvantGardes and many others in high end audio. But it is this kind of efficiency (+100dB) that you really want to be looking for if you want the most out of an SET. You're not going to get there with higher powered SETs as the demands of the output transformer design are prodigious; the price you pay for increased power is reduced bandwidth, to the point where in most cases the term 'hifi' can't be used.