I owned an OTL amp for 8 years and then switched to SET. No one has mentioned that OTL amps require many output tubes. For example, my OTL amp had 8 output tubes. The obvious issue is that OTL generates a lot of heat, but also with that many tubes, there is more potential for tube hiss and other tube related noise. I was always tracking down a gremlin. My OTL amp always had tube hiss through the speakers, but the more annoying thing was dealing with tracking down the cause of humming noise that would arise. When my amp was quiet (albeit with the hiss still there), it was glorious. I’m not saying that other OTL amps such as Tenor or Atmasphere have noise related issues, as I have no experience with those brands, but mine did.
My current SET amp has been 100% reliable since I got it over 5 years ago and is the most quiet tube amp that I have ever owned. I have gone through a lot of amps over the years. One thing I really enjoy about my SET amp is that I can more easily tell the difference between tubes, cables, and source components. With my OTL amp, the differences were much more subtle. For me, I would not say that OTL is "superior" as that has not been my experience. I would like to re-visit OTL one day, but I am thoroughly enjoying my SET amp so there is no rush.
My current SET amp has been 100% reliable since I got it over 5 years ago and is the most quiet tube amp that I have ever owned. I have gone through a lot of amps over the years. One thing I really enjoy about my SET amp is that I can more easily tell the difference between tubes, cables, and source components. With my OTL amp, the differences were much more subtle. For me, I would not say that OTL is "superior" as that has not been my experience. I would like to re-visit OTL one day, but I am thoroughly enjoying my SET amp so there is no rush.