I have Mr. Walkman’s firmware which allows 2x gain. Even so, I have to set volume at 95-105 of 120.I almost cannot believe that you can drive Caldera from 1A with good result. When I demoed Caldera and Atrium in CanJam, I immediately noticed that Caldera sounded so consistently when I switched between SS and Tube. For my Atrium, it is very different. I haven't tried my Atrium from 1AM2, I probably will when I find a converter though I doubt it will perform well.
But it sounds excellent, and while it sounds more well-controlled and powerful with my solid-state desktop amp, it’s not night and day. I have been pretty happy with my Atrium Closed as well when driven by the Sony.