After years of hearing this debate, I ended up getting a pair of Atma Sphere MA-1's and I have to say they are the finest amps I have ever owned.
As Ralph pointed out, they do get hot, and in summer can challenge the AC system.
So, I also bought a pair of Ayre MX-R's.
I have to say they really give the Atma's a run for the money.
Perhaps it is the zero feedback in both designs. I don't know.
But, at least I can use the tubes in winter and SS in summer.
HTH
Bob
As Ralph pointed out, they do get hot, and in summer can challenge the AC system.
So, I also bought a pair of Ayre MX-R's.
I have to say they really give the Atma's a run for the money.
Perhaps it is the zero feedback in both designs. I don't know.
But, at least I can use the tubes in winter and SS in summer.
HTH
Bob