SET 45 Amp Driving Dynamic Speakers

"Technical facts" by no means tell the entire story.  As has been mentioned on this site numerous times,  measurements and specifications play a fundamental role primarily in determining electrical matching/suitability of audio components.  So it is an effective screening tool. I'm unaware of anyone here disputing this point. What determines if someone will be happy with chosen components is listening to them following the initial screening. It's a two stage process. For my purposes listening is required to make judgements regarding the merits of audio products. Others may utilize alternative methods. 
Charles, 

Tommy,

I’ve heard all forms of demos at shows also, including very expensive high quality SETs using similar very large efficiency horns (with correspondingly stunning results).

The best thought out and executed ones, SET or otherwise, always exceed those that are compromised in some way.

Because of the few watts used, the difference between the best (large GOTO custom horns and bass bins comes to mind) and worst (Zu Essence is one that comes to mind, fine for acoustic jazz, very meh for rock/pop) SET demos I hear are perhaps among the most extreme possible.

So the ante is upped whenever one device asks more of another. That can be a SET asking more of the speakers (be more efficient and an easier load) or the speakers asking more of the amp (give me lots of clean undistorted power please).

Lots of ways to skin the cat acceptably perhaps but only only a few ways to really do it right/best.

I feel I’ve done it pretty well the second way currently at home (compared to the stellar SET demo for example I have heard as a reference among others) and look forward to giving the other way a try someday starting with a separate system on a smaller scale that I can compare and contrast with my in home larger "reference" system.

In the end its all a matter of expectations and how well things are executed together to meet them.

I don’t know of anyone who begins their entry into High End audio with SETs.   Most everyone I know who enjoy these amps tend to be very experienced and have owned quite a few different amplifiers before hand. This scenario would certainly describe my journey. Having gone through various good quality SS and push pull tube amplifiers helped me quickly recognized the significant attributes of a SET. Tommy I suspect that the 45 SET I isn’t your first amplifier.
Charles,

Charles,

I suspect there is a significant sized yet small minority out there that do venture into SETs or their like initially for various reasons, but on a limited budget like most first timers.

FOr example Glow audio sells a very popular and stylish looking SEP amp, the Amp 1 that will look quite nice in many homes. I’ve heard it at shows and it works quite well with many speakers. Jolida has various low wattage tube amps (not set) that also sound quite nice, like the FX-10 that I ’ve also heard.

These are very viable but well "compromised" options like all the rest for similar cost that some newbies might consider right off the bat.

The thing is speakers for an uncompromised set system tend to be larger and quite expensive and not something that will appeal to many.

Whereas with newer Class D amp technology in particular, one can create a small, manageable and reasonably uncompromised system quite easily with many options and for fairly modest cost.

Again, its all a matter of expectations and what limitations one is able to deal with effectively.

When it comes to tube amps, for me the fewer tubes the better. That’s where a SET amp has appeal for me. Thing is my Class D based SS system sounds so good, I have little incentive to look elsewhere other than sheer curiosity and the fact that I think this stuff is fun. I’m very glad I tried the Class D option first. So is my power bill. I’ve opted for modern technology that is also more efficient and green (and also best match my speakers around which my system is built for best results) than older amp technology that is the exact opposite and requires things be built around it for best results. :^)

Either way is perfectly valid and of course neither will appeal to all which is what makes the world go round.

I think that most often people who are SET fans arrive at that point after going through a range of other choices.  Low-powered SETs tend to be an end-point only after a long search because it takes some experience finding the relatively few speakers that are compatible with such amps (many high-efficiency speakers are highly "colored" as far as their tonal balance so you have to find the few that are not so odd or learn which "color" works for you).  It can also mean giving up a little on some of the more obvious attributes (like extremely deep bass response and bass punch) for the more sublime attributes of SET amps and compatible speakers that one learns to appreciate after long-term experience.  So, in that sense, I agree with Charles.

But, in this day and age, where "knowledge" so freely flows on the internet, I can see Mapman's point that a lot of inexperienced listeners could be seduced into trying SET amps at the outset (it took me YEARS before I even learned of their existence, today just google "best amp" and you are there).  I fear that it is the case that many are tempted to try SET amps with incompatible speakers and/or assume that cheaper SET amps will do the trick because they should not cost that much to manufacture (because they a simple and have few parts).  The problem with that is that those parts can be very expensive to get right, particularly the large, air-gapped output transformers that can handle the high standing current in the primary without over saturating.   You will find a lot of internet posts from those saying that the SET amps they heard are crap; I bet that a lot of this comes from listening to such "bad" setups (easier to be WAY wrong with SETs that with any other kind of amps).

While I agree that it is far easier to get quite decent sound at a reasonable price from Class-D amps, I have not heard any "all out" assaults on top quality sound that involved such amps.  I admit that I haven't heard too many in high-end systems utilizing Class-D amps, but, those that I have heard were somewhat disappointing (e.g., Devailet and Rowland) because they just sounded a bit dull and un-engaging.   In a lower-end system, I thought that a Bel Canto amp sounded pretty good for the money.