SET's aren't limited to single driver full range speakers or horns, they just need efficient speakers. I have some conventional Athena F2 floorstanders that are 91db sensitivity that work well with a 3.5 watt SET and can play louder than anyone would care to hear. I also have a pair of Axioms that my SET's can drive with ease. Most folks don't realize how powerful that first watt really is. There are 10 times the dynamic range in the first watt than there is in the second watt. While I don't drive my amps to clipping levels, SET's unlike SS can still sound great when clipping. SET's usually run in class A and many Klipsch owners prefer SET's to other types.

Personally I crave the micro detail I get with a SET paired with a crossover-less HE full range driver. A conventional crossover will turn a significant portion of that first watt into heat before it ever reaches the driver so it's robbing you of both detail and power. I've a few digital and tripath amps which I like but they come up short compared to SET's. They're accurate but lack feeling and can't float notes in mid-air like a SET. I want to hear and feel "the wood" of an instrument and the SET gives me this experience.