I have heard the Orangutans with a 211 SET amp and the combination sounded nice. If it is an easy load, and truly 96 db efficient, it should work reasonably well with even lower-powered amps. To me, the key is "easy" load more so than high efficiency. I have heard the notoriously inefficient Rogers 3/5A (15 ohm version) used with a 5 watt amp and the combination sounded very good, with no hint of clipping even at fairly high volume.
A lot depends on how loud you require the system to go. Most SET users actually appreciate the fact that their systems can sound very full, dynamic and exciting at surprisingly modest volume levels.
But, if you insist on playing SETs very loud, what you will first notice is that the music actually sounds dull (the dynamics will be compressed long before very obvious distortion from clipping is heard). I think that the kind of music where the limitations of SETs can be best heard is large choral works, particularly works without instruments (e.g., Rachmaninov's Vespers with a good Russian choir)--it is easy to hear the voices become muddled and inarticulate.
I have heard Trenner and Friedl speakers (can't remember the models) and they sound very good to me--they have the great dynamics that one finds mostly with high efficiency speakers.
I personally find that there are very few commercial speakers that I like that are SET friendly, particularly if one is insisting on high volume level and a commensurate efficiency pushing at 100 db/w or more. That usually means horns, and most horn systems have a lot of midrange coloration that one has to either learn to love or ignore. The systems I have heard that minimize horn colorations are custom built, use very hard to find old drivers or use some very expensive new drivers. On the other hand, if one is willing to live with restrictions on use at extreme volume level, quite a number of good speakers can be used, such as Audionote, Spendors, even ProAc.
A lot depends on how loud you require the system to go. Most SET users actually appreciate the fact that their systems can sound very full, dynamic and exciting at surprisingly modest volume levels.
But, if you insist on playing SETs very loud, what you will first notice is that the music actually sounds dull (the dynamics will be compressed long before very obvious distortion from clipping is heard). I think that the kind of music where the limitations of SETs can be best heard is large choral works, particularly works without instruments (e.g., Rachmaninov's Vespers with a good Russian choir)--it is easy to hear the voices become muddled and inarticulate.
I have heard Trenner and Friedl speakers (can't remember the models) and they sound very good to me--they have the great dynamics that one finds mostly with high efficiency speakers.
I personally find that there are very few commercial speakers that I like that are SET friendly, particularly if one is insisting on high volume level and a commensurate efficiency pushing at 100 db/w or more. That usually means horns, and most horn systems have a lot of midrange coloration that one has to either learn to love or ignore. The systems I have heard that minimize horn colorations are custom built, use very hard to find old drivers or use some very expensive new drivers. On the other hand, if one is willing to live with restrictions on use at extreme volume level, quite a number of good speakers can be used, such as Audionote, Spendors, even ProAc.