A good OTL has the immediacy and presence of a SET amp while generally providing even better bass response. You will also hear a lot of people using the word transparency. OTL's have a liquid yet very neutral and open sound. I love both OTL and SET amps. I own an Atma-Sphere S30 as well as 45, 2A3, 300B and GM-70 SET amps. I would not part with any of them. To my ears the SET amps colour the sound more than an OTL does but the sound is so gorgeous I don't care to be a purest. I find I use the S30 OTL and GM-70 the most. They have more power than the smaller SET's and I find they are also better balanced - not unduly emphasizing the midrange like the 300B does (which can be wonderful in its own right depending on my mood). I think all audiophiles should experience both a SET and OTL amp as a right of passege during their audio journey.
Thought on OTL tube amps
Just curious....how do these sound/perform compared to tube amps with transformers? Why do you prefer one or the other? Any particular brands of OTL amps you would recommend listening to? You can see my system on my tag here...listen mostly to rock and roll with a smattering of jazz and a bit of classical once in a while. The next stop on my amplifier adventure is an OTL model, and I have no intention of trading it for either SET I currently have, as I'm very happy with both. One of the ways I enjoy experimenting with different "sound" is by switching up the amps. Just trying to solicit some opinions, of which I know there are many strong ones here at A-Gon. Thanks in advance!