Atma-Sphere vs Pass Labs Class A


Has anyone directly compared the atma-sphere amps versus a Pass Labs Class A design? I have been running OTL tube amps and found nothing I like better in terms of openness, natural sound and transparent, realism, but in the summertime they are very hot running.

What would be the closest in sound to the atmasphere in a solid state design?
warrenc
Warren, have you lived with some Class A solid state amps that run cooler than Class A tube amps (of comparable power output)? My experience is that it's the Class A operation that makes the amps run so hot, not that it's tube vs. solid state. Just curious if your experience is different than mine.

I've not compared the Atma-Sphere with the Pass Labs, and yes I sweat through the warm weather with my A-S MA-2s, too.
I have compared Atma-Sphere M-60 to Pass Labs XA-60.5.

However, one was a mismatch with my speakers and the other was not.

It will surprise me if anyone has compared these two brands on speakers that match both equally well.

In terms of heat, I would say both amps were about the same, with the Atma-Sphere perhaps running a bit warmer, but not by much. The Pass Labs will warm a room.
It will surprise me if anyone has compared these two brands on speakers that match both equally well.

Very well said. They are designed with fundamentally different philosophies, and among other things have drastically different output impedances. Ralph has an excellent paper on this at his site:

http://www.atma-sphere.com/papers/paradigm_paper2.html

Regards,
-- Al
Thanks for the input. All other things being equal, I guess given the lack of difference in heat output, I will stick with what is working well for me now.

Al, thank you for the link to Ralph's paper...
XA60.5 draw 200W per chassis; M-60 draw 300W per chassis.

Dealer disclaimer.
I'm sure Ralph would tell you if your speakers would be a good match for his amplifiers. 300 series Rowland amps run quite cool and are very "tube like".