I have a Wyetech Topaz. It is a fabulous amp with the right speakers. As long as your speakers can be driven by 23 watts and has a kind impedence, there isn't much out there that is better. It has great bass power and articulation, and outstanding delineation of instruments and vocals. Unlike other SETs, it is very neutral and natural sounding. Read the TAS review by Scot Markwell, and there are some other comments about it on the internet. I've only heard the Atmosphere M60 Mk2s. They were very good. I'm sure the M1s are very good also. But Atmasphere amps have boo-coo tubes that heat your room and light it up like a nuclear powerplant. The cost of re-tubing must be pretty high.
I've had OTLs in the past. I've always found the in-your-face, crystal clear sound they provide a bit fatiguing after awhile. An exception was the Joule Electra OTL, which is a much more mellow OTL sound. If you like what you are hearing now, stick with it.You probably can't go wrong either way, but I don't think you are going to be able to demo a Wyetech in your system. They are an extremely limited production amplifier (mine is the latest - serial #37 after two years of production). Another consideration would be the Tenor OTLs, if you can find them used. There is (or was) a 15 watter for sale on Audiogon, but I don't think that would drive your speakers. They do make a 75 watt OTL that is supposed to be extremely good. They use fewer tubes than the Atmospheres, and have gotten fabulous reviews.
I've had OTLs in the past. I've always found the in-your-face, crystal clear sound they provide a bit fatiguing after awhile. An exception was the Joule Electra OTL, which is a much more mellow OTL sound. If you like what you are hearing now, stick with it.You probably can't go wrong either way, but I don't think you are going to be able to demo a Wyetech in your system. They are an extremely limited production amplifier (mine is the latest - serial #37 after two years of production). Another consideration would be the Tenor OTLs, if you can find them used. There is (or was) a 15 watter for sale on Audiogon, but I don't think that would drive your speakers. They do make a 75 watt OTL that is supposed to be extremely good. They use fewer tubes than the Atmospheres, and have gotten fabulous reviews.