SET amplifiers from 6-12 watts can drive most of my horn collection to Rock concert SPL levels in home. But you do have to have a massive horn loaded design to do this and it must be designed for lower power. I cheat a bit I have 1 system that is horn loaded to 75hz and with that I run a powered bass system this can run on the wee output of a 45 SET amplifier and still produce peaks of 108db 3 meter before its going into massive distortions. I know many do not mind when the SET amp does so its a bit pleasant but I find it fatiguing and prefer to not push the amp or loudspeaker. I have no limits on music I play no limits on SPL but still no free lunch. Hoffman’s Iron Law of Speaker Building
1) Bass Extension
2) Efficiency
3) Small Enclosure
The law is that you can only have two of these three attributes in speaker building. Ideally we would want all three, we want speakers with good bass, can play really loud, and are small. Unfortunately we cannot have all these.