A good place to read about SET is the SET forum on Audio Asylum. Very large archive of information to learn about SET amps.
To me the biggest SET magic is the immediacy factor. A SET system can sound bright, soft or somewhere inbetween, but the music always seems to be more intimate or in contact with the emotion. That gives a live feeling that other system often found lacking. Whether this factor is true to the recording is debatable, but I don't really care that much about accuracy. I am just here to enjoy the music.
Eric
To me the biggest SET magic is the immediacy factor. A SET system can sound bright, soft or somewhere inbetween, but the music always seems to be more intimate or in contact with the emotion. That gives a live feeling that other system often found lacking. Whether this factor is true to the recording is debatable, but I don't really care that much about accuracy. I am just here to enjoy the music.
Eric