High efficiency speakers

I understand your problem perfectly, because I embarked on a similar journey myself. Click on "my system" to see what I ended up with. My setup is not without its problems but I am working on a solution to it.

The problem with hi-fi is that you can go the "accurate" route, which usually means big SS amps and ineffecient speakers, or you can go the "high efficiency" route. The former gives you accurate but sterile sound, the latter has benefits of simpler electronics, extremely fast speakers, purer sound, but usually involves compromises such as cost, size, coloration, and lack of bass. This is a harder route to take, and you will have to think hard and match carefully if you are going to succeed.

There are a few types of designs you might like to consider. Front loaded horns (e.g. Avantgarde), back loaded horns (Lowther, Rethm, Tannoy), high efficiency conventional speakers (WLM, Zu), and compression drivers are the main technologies involved.

By far the most similar to speakers you are used to would be speakers by WLM and Zu. I have heard both - not a fan of the Zu, but I do like the WLM's very much. As a bonus, they are very reasonably priced.

The Tannoys would be a good pick if you could get over the styling. They are by no means uncolored - in fact they are very heavily colored. But it's a very appealing kind of sound.

Dukes Audiokinesis loudspeakers might run on your 18 watts hes a great guy products very well though out.

Amfibius, your Acapella speakers look very cool indeed. Aesthetics is important to me. While my little Kharma's are not perfect match for my soon-to-arrive SET amps, and have limp bass, at least my wife doesn't complain. If i brought in the Avangarde Trios, I think she would scream:). So I need to avoid big broad cabinet designs if I could and there goes Tannoy.
Alec

My bias against powered bass in high efficiecy speakers is just a thought that since these designs use transistor amps for ther woofers, are they forgoing the supposedly sonic superiority of SET over SS amps (even in the bass quality.)?

I don't know how you would actually like it, but before you jump to conclusions about it you should perhaps try listening to some implementations of what you are describing here (basically you're talking about bi-amping). I do think it takes some skill and knowledge, but have heard it done well, though I cannot say it was with a SET amp in the mix. As far as the sonic 'superiority' of SET over SS - IMO (this is coming from a big SET fan who has used 300B 8 watt SET amps in my main system for around 8 or 9 years now) the allure of SET is all in the midrange purity and that magical holography that no other type of amp does so well (OTL is a nice alternative though and comes pretty damn close). I haven't heard any SET amps that can do tight convincing bass as well as an SS amp - that's not to say one doesn't exist, but I haven't heard it if it does. When it comes to pushing those larger woofers that really move a lot of air fast to create the convincing bass, the lower powered amps just are not up to the task when compared to more powerful alternatives. I'd also highly recommend SET and horns, and would have mentioned vintage Klipsch as well but your tastes seem to run in the more exotic realms. Klipschhorns and SET were made for each other. Horns and SET in general are a great match, but they can also be a matter of taste as the sound is unique. I love it myself, but have also heard front loaded horns that bore me to tears or make me want to go running from the room. I tried Zu Druids for a while and didn't warm up to them at all. The success of your implementation of SET and a particular pair of speakers will also be determined by the kind of music you listen to, how loud you like to listen, and the volume of the room you are listening in. Most of the music I like the best is well suited to SET - it is simple, acoustic and or vocals in small arrangements. If you are into densely arranged orchestral, jazz or rock music IMO there are better choices in amplification than SET, and the idea of 'superiority' goes right out the window in comparison with an excellent SS amp when listening to these materials regularly. In this sense SET is kind of a one-trick-pony. It is certainly not the Swiss army knife of amplification. Don't get me wrong, I love what it does well - in those realms it is king when put together with the right speakers. You are right to carefully research that specific interface as it is more critical than ever when using a SET amplifier.

Good luck!

Specs don't always tell the whole story.

My ProAc Response 2.5s are rated at 8 ohms and 86 dB. When John Atkinson measured them back in the day, he calculated 83 dB!

Yet they work wonderfully well with my Cary 300B-based SET, rated at a whopping 14 watts!

Part of it is the real-world (not claimed!) 8 ohm load--Atkinson's graph shows them barely dipping below 8 over the whole 20-20k range.

BTW, I was turned on to this synergistic combination years ago by Arnie (founder of A'gon) in his previous incarnation as owner of Accutronics of Ann Arbor, MI. According to Arnie, Dennis Had used (at least back then) ProAcs to voice his Cary amps.