The S-30 is quite a nice amp and compact so it's a space savor. At a minimum I would get the power supply boost if you were to purchase one. You may also consider modifying it so the feedback loop is disconnected, even though Ralph uses an extremely low amount of feedback, or no feedback in his designs.
As for differences, I just find the M60 provides a more realistic sound stage with better imaging and separation of instruments, as well as more dynamics. The sound in the lower frequencies is where I hear the main difference with the M60 providing more of a good thing there. I think those who pan the bass in Atma-Sphere amps or consider it lean are mistaken. In addition, this whole thing about "tight" bass that I hear thrown around like ketchup on a burger is a misnomer to me. To me "tight" bass as I have heard it defined is a coloration and not something I want in my system. I find the M60 to provide a very natural presentation in the bass area.
Any Atma-Sphere amp, as well as any well designed OTL is going to give you transparency and detail the likes you have not heard before, assuming they are a good match for your speakers. The Music Reference OTL-1 is no different, although Roger and Ralph differ on their preferred platform for circuit design, Futterman vs. Circlotron, as well as use of feedback.
The OTL-1 was designed for high efficiency speakers or those who prefer low level listening. I've used mine on speakers of lower efficiency with good results as long as you keep the volume within reason. It is direct coupled with no output capacitor and a servo manages DC offset. The main thing I enjoy about the amp is it's flexibility. Four taps employ an autoformer that allows the amp to put out 10 watts into a 2, 4, 8, or 16 ohm load. Feedback can be taken from the same tap your speaker is connected to, or any other tap to adjust gain and damping (versus Atma-Sphere the OTL-1 has much lower output impedance). There is also a direct tap that bypasses the autoformer. In this case you get 1.7 watts into 4 ohms, 3.5 into 8 ohms, 7 into 16 ohms and 14 into 32 ohms.
As for differences, I just find the M60 provides a more realistic sound stage with better imaging and separation of instruments, as well as more dynamics. The sound in the lower frequencies is where I hear the main difference with the M60 providing more of a good thing there. I think those who pan the bass in Atma-Sphere amps or consider it lean are mistaken. In addition, this whole thing about "tight" bass that I hear thrown around like ketchup on a burger is a misnomer to me. To me "tight" bass as I have heard it defined is a coloration and not something I want in my system. I find the M60 to provide a very natural presentation in the bass area.
Any Atma-Sphere amp, as well as any well designed OTL is going to give you transparency and detail the likes you have not heard before, assuming they are a good match for your speakers. The Music Reference OTL-1 is no different, although Roger and Ralph differ on their preferred platform for circuit design, Futterman vs. Circlotron, as well as use of feedback.
The OTL-1 was designed for high efficiency speakers or those who prefer low level listening. I've used mine on speakers of lower efficiency with good results as long as you keep the volume within reason. It is direct coupled with no output capacitor and a servo manages DC offset. The main thing I enjoy about the amp is it's flexibility. Four taps employ an autoformer that allows the amp to put out 10 watts into a 2, 4, 8, or 16 ohm load. Feedback can be taken from the same tap your speaker is connected to, or any other tap to adjust gain and damping (versus Atma-Sphere the OTL-1 has much lower output impedance). There is also a direct tap that bypasses the autoformer. In this case you get 1.7 watts into 4 ohms, 3.5 into 8 ohms, 7 into 16 ohms and 14 into 32 ohms.