The Atma-Sphere amplifiers are totally stable and absolutely reliable. The output tubes are very rugged tubes and will run for a long, long time. When replacement time does come, they are not terribly expensive and they do not have to be matched. A-S sells them at very reasonable price.
The bias on the amps remains very stable, in my experience. Over the first 30-days, you will need to monitor/adjust it every few days, but once it settles in, it will stay very stable.
All of the Atma-Sphere amps operate in Class A. Any output device run in Class A, solid-state or tube, throws off a fair amount of heat. How much heat depends on which model amp you're talking about due to the varying number of output tubes. The M-60s are modest heat producers compared to the MA-2s. The MA-2s, which I own, will definitely warm up a room.
I agree with the recommendation to visit the Atma-Sphere Owner's Group web site, www.otlamp.com The folks who post there would be happy to answer other questions you may have.
The bias on the amps remains very stable, in my experience. Over the first 30-days, you will need to monitor/adjust it every few days, but once it settles in, it will stay very stable.
All of the Atma-Sphere amps operate in Class A. Any output device run in Class A, solid-state or tube, throws off a fair amount of heat. How much heat depends on which model amp you're talking about due to the varying number of output tubes. The M-60s are modest heat producers compared to the MA-2s. The MA-2s, which I own, will definitely warm up a room.
I agree with the recommendation to visit the Atma-Sphere Owner's Group web site, www.otlamp.com The folks who post there would be happy to answer other questions you may have.