Atmasphere amps trustable?

 I have thought about matching these with my single-driver speakers but reluctant to do so based on previous experience.

If you are going to run a lower-powered speaker like a Lowther, its in your best interest to install a speaker protection fuse in the circuit if you plan to use any amplifier that can make way more power than the speaker can handle! That would include most of our amps.

In a nutshell, we would not be in business for 40 years (so far) if our amplifiers damaged speakers! But common sense should always be applied when matching audio gear.

Power tubes can blow though, and I don’t know how well protected Ralph’s amps are if this happens or what kind of warranty Ralph offers.

In the old days we put way too many fuses on the amps as we were concerned about the effects of tube failure. As time went by we got the number down to 3. The fuse by the power cord blows if the amp tries to make too much power, and this has proven very effective for speaker protection since we started using this system, which was about 25 years ago or so. The amps are warranted 3 years (although we are not particularly picky about that and the warranty is transferable) and tubes are warranted for 1 year.

atmasphere, I found this article interesting. I do not claim to understand much of it, but appreciate and like what I do read/understand. It speaks even more specifically to your specific implementation of Circlotrons. There is even a blurb about loudspeaker safety as well (in addition to what you have previously stated). To an extent I would consider you a pioneer in your field. Not sure if you had anything to do with the text portion of this article, but you and your company are credited throughout. 

https://en.wikipedia.org/wiki/Circlotron

I stand corrected.  My OTL amps were indeed produced by Fourier Components in the late 1990s.  BTW, to my knowledge, Atma-Sphere is one of the few, if only, OTL amp companies to survive for any length of time.  Probably a testament to their reliability.  Most of the others, NYAL, Futterman, Fourier Components, Counterpoint, Silvaweld, Prodigy, for example, have gone bankrupt.  I sense a trend here.

^^ Thanks for that, I don't recall ever seeing that page before. It has some omissions (probably should have mentioned GAS and BAT, no mention of Graaf, who was the only Circlotron amp manufacturer to employ the Cecil Hall circuit in modern times) and certainly glosses over some detail (as the Cecil Hall amplifier was a bit of a variant compared to what's shown on that page). 

I came home one time, and I found my M-60 Mk II's in BED with my Spendors...I will never get the image out of my mind, and I sold them both the next day. By far the most two-faced, untrustworthy amps I've ever bought.