Herman,
IMHO, SETs are distortion generators. They can make a Yamaha violin sounds
like a Stradivarius. Like guitar amps, they should be considered more like a
musical instrument than audio reproducing equipment. Can SETs sound
good? Sure, I like them too. I used to built them when I was much younger.
But they are not Hi-Fi amps.
I know many people will disagree. Since we are talking about Hi-Fi here, Hi-
Fi or High Fidelity means faithfully reproduce. If an amp can make a Yamaha
violin sounds like a Stradivarius, it is not Hi-Fi, no matter how good it may
sound to some people.