Hello folks- I was going to post this in another thread, but it got kind of long, and given the recent apparent interest in all things tube related, I thought that this might be helpful to the newbs. I hope to hear from the old hats, to correct me where I'm wrong and share their input. I don't mean for this to be a defense of SETs, just an exposition of what is actually going on. So we occasionally hear from someone about how great SETs sound, how they do this and that better than ss, etc. But what is really going on? Are those guys crazy? In need of an audiologist? To figure out what is really going on here, it's important to know some general basics about tube vs ss circuit behavior. Here is a good article from an engineering perspective and citing reputable primary sources: http://www.theaudioarchive.com/TAA_Resources_Tubes_versus_Solid_State.htm At the end where they're wrapping it all together, and particularly regarding the behavior of tube circuits when overloaded, they write: Now, compared to any other amplifier, one of these low watt SET amps is almost always operating in this 'overload' area. High amounts of measurable distortion. But the SET's distortion pattern is also quite different than the other approaches. Push pull tube amps (and SS for that matter), squelch 2nd order harmonic distortion but also squish the distortion out to higher orders at much lower levels. (None of us would run our amps into clipping anyway, would we, so it shouldn't even matter.) SETs do not filter 2nd order distortion, with a heavy bias towards lower orders in general. One huge factor which allows it to misbehave is called 'perceptual masking'. This is simply the phenomenon of lower harmonic components being overshadowed by the fundamental. 2nd order harmonic distortion is virtually indistinguishable from the signal as 'distortion' until it gets quite high (you are much more tolerant to it than you would think). As the harmonic content extends away from the fundamental tone, it is masked less, and becomes objectionable at a lower level. Also keep in mind what the rising 'edge harmonics' referred to in the article are doing as well. They add subjective loudness, but not necessarily perceived as distortion, even though it is. 'So what' you might be thinking. It's still a non-linear amp with low power. It doesn't make rational sense to even try, over conventional gear. Is it a good amplifier? Technically, no. It's a low power, signal-mangling nightmare. But it also can defy rational expectations. Perceptual masking allows SETs to get away with more distortion. The overload characteristics of SETs has them constantly embellishing the signal with harmonic content, which, as stated goes from unnoticable to gross clipping over a pretty wide range. Within that range, the subjective impression of the overload characteristics is uncompressed headroom, not distortion. As the reviewer of the Decware amp in that cnet review might have said, it puts the meat on the bones. The problem is, if you don't know this stuff before hearing one, their sonic difference is misleading. Counterintuitive doesn't begin to cover it. Compared to solid state, they sound much richer and more well rounded, even if it's harmonic embellishment. Your ears don't recognize it as such. It's mind boggling that such puny power can sound so good to the uninitiated. None of this makes SETs good amplifiers, but I think this does explain why they can cast a spell. It's tenderized sound which some find irresistably pleasant. Some folks write it off completely without hearing it. I can respect that, SETs are strictly for the hobbyists. Some folks try it and don't like it's limitations. Some folks try it and say 'This is what I've been seeking all along' and live happily ever after. It's not the magic nonsense the uninformed would lead you to believe, nor is is as bad as some of the more objectivist types would lead you to believe. It's just another way to make noise in your house. I could be completely off my rocker with this, so feel free to tear this to shreds.