Efficient, affordable speakers for SETs?

I’ve owned Vandersteen 1B speakers for a long time.They are easy to drive and have a 6 ohm impedance.

The experience that I can share—and that hopefully will be of some benefit to others—concerns just how sensitive a speaker should be in order to capture what @mglik calls “SET magic.” I repeated the same mistake multiple times (meaning with multiple speakers) over roughly 15 years—clinging to the belief that a speaker with a sensitivity rating in the low/mid-90s was plenty “SET friendly.” I didn’t realize how wrong—practically and conceptually—my belief was until I started experimenting in the high-90s. Then low-100s. And now approaching 110 with my current system (which is a multi-amped 5-way with single-ended amplifiers driving 4 of those channels).

Ultimately, the mistake I kept making was having no appreciation for what @atmasphere pointed out above: this amplifier topology shines when it’s not stressed, and the “20-25% of full power” figure sounds right. On the flip side, @mglik described some telltale sounds of an over-burdened SET amp: “dirty,” “colored,” “soft clipping.” I don’t think it has to be that way.

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. The SET amplifiers with DHT output stages with which I’m familiar haven’t been powerful enough or “grippy” enough for this duty ... and that has led to anemic bass. Outside of some highly-specialized single-ended designs, the benefits of push-pull topology shouldn’t be overlooked, here.

One thing that might be beneficial is to get to know (but not necessarily acquire—restrain yourselves) some classic speakers from the era. (WE and Altec for starters.) These were, quite literally, “speakers designed to work well with SETs.” Open-minded listeners tend to come away from this kind of experience with a first-hand appreciation of the possibilities—and a very firm resolve to figure out how to capture some of “that sound” without inviting an albatross into the living room.

With that, I don’t mean to imply that there are no valid recommendations earlier in the thread. There may be—but I personally struggle to connect with this stuff absent any context. Listening space (a bedroom? a barn?) is super-relevant, here ... as is potential for a powered subwoofer, upstream component specs, listening habits and preferences, etc. For whatever reason, single-digit WPC and a mere handful or two of parts seem to place an increased premium on excellent overall system matching.

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.

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.

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

The Charney Voxativ speakers are very interesting. Looks like the cheapest way to get into the fabulous Voxativs!                                   

Yes the Charney’s are cost effective versus the Voxativ offerings. Here's a little secret Charney sounds way better at 1/3 the cost! I had the opportunity to listen to the Charney Companion with  Voxativ AF2.6 drivers against the Ampeggio. No contest! The Companion bettered the Ampeggio in every area! 

If you can swing it and your room is large enough the AC2.6 is the way to go.  The 8” driver will give you more all the way around. 

FWIW its impossible to design any hifi audio product to favor a certain genre of music. 

I, mostly, disagree with this statement. Regarding amp/speaker, one cannot say that a high powered amp is not designed to supply the juice needed for high sound output. And that a large speaker system is not designed similarly?
Another point is that I do believe, especially limiting the low frequency output of my 90db flat 8 ohm Tetra 506s with a good Rel sub gives me "the most" out of speakers. Taken into consideration that the voicing of the speakers was with 8 watts of 300B. I do understand that a 100db+ speaker is an entirely different story from a physical/tech perspective.
Surely, an Ocellia is not a "Rock and Roll" speaker and is more suited to the dynamics of Jazz. Is it not greatly contingent on a speaker's physicality?
Just a personal note to you, maybe 30+ years ago I called you thinking of buying one of your amps to power my Quad 57s. You graciously turned me away saying that my then Bedini 15/15 was a great amp for the 57s. A quite belated thanks!