The 5-7 watt SET amps that I have heard do surprising well with even moderately efficient speakers in many cases with many kinds of music. They have their unique charms within their limitations. It takes very large very efficient speakers to get around the limitations completely based on what I have heard which to date supports my general understanding of the physics involved in driving speakers optimally.
I have only heard one SOTA such full range system where dynamic headroom seemed unconstrained, a very large multi unit custom GOTO horn system, similar to Avantgarde with separate bass modules in appearance/design, run off a pricey Audio Note SET amp. I'm sure there are others but the key is to havbe very large very good, very high efficiency speakers designed specifically with SET type amps in mind.
But on a smaller scale, I have heard various very nice sounding SET based systems with smaller speakers, but each of course has its technical limitations that may or may not matter depending. THis stuff is as much about personal preferences as anything, though for me. With SET amps and many smaller speakers, they still can as long as higher volumes, low end extension and optimal dynamics are not key ingredients in the preferred recipe.
I have only heard one SOTA such full range system where dynamic headroom seemed unconstrained, a very large multi unit custom GOTO horn system, similar to Avantgarde with separate bass modules in appearance/design, run off a pricey Audio Note SET amp. I'm sure there are others but the key is to havbe very large very good, very high efficiency speakers designed specifically with SET type amps in mind.
But on a smaller scale, I have heard various very nice sounding SET based systems with smaller speakers, but each of course has its technical limitations that may or may not matter depending. THis stuff is as much about personal preferences as anything, though for me. With SET amps and many smaller speakers, they still can as long as higher volumes, low end extension and optimal dynamics are not key ingredients in the preferred recipe.