Nice blog post on SETs recently, here.
A few excerpts. It’s not a long post and worth a read:
"The SET’s very existence calls into question fundamental beliefs and assumptions we routinely make about technical performance, sound quality, and the correlation between them. These amplifiers expose a crack in the edifice of audio engineering theory that is based on the conviction that an amplifier can be judged by its technical specifications or measured performance....
This paradox arises because the technical measurements that attempt to quantify amplifier sound are simply inadequate and incomplete....Predicting an amplifier’s sound quality or judging it to be good or bad based on existing criteria is like looking at a few still images from a movie and then attempting to discern from those static photos the movie’s plot, characterizations, dramatic arc, and meaning.
The SET exposes the fact that certain aspects of amplifier performance are not quantified by the traditional measurement arsenal....
Some will suggest that listeners are merely responding to the SET’s euphonic distortion—that the SET sounds good because of its distortion rather than despite it. There’s no question that the largely second-harmonic distortion component of an SET is much more sonically benign than the upper-order distortion components of Class AB solid-state amplifiers. But a first-rate SET amplifier’s magical qualities go far beyond this simplistic interpretation. The SET’s resolution of inner detail that, singularly, conjures up a strikingly vivid picture of the instrument creating the sound is certainly not merely a euphonic second-harmonic distortion artifact....
This essay is neither a renunciation of all amplifiers other than SETs nor an evangelical campaign for the world to embrace the single-ended-triode amplifier. SETs are limited in the loudspeakers they can drive, exhibit other practical drawbacks, and are certainly not for every listener...."
https://www.theabsolutesound.com/articles/the-single-ended-triode-paradox/
