AJ,
I am not asking that question. I made an observation that my amps sound better after they have been on for a while. I notice this if listening from cold. When I turn them on and leave the room for an hour and then return to listen, I don't notice this change with further listening. I conclude that the changing sound of my system during this first hour or so has something to do with my Class A amps reaching some operating temperature before the sound stabilizes. I can not explain why I observe this, nor can I prove if or why this happens. I can not explain why Pass Labs notes this in their manual. I don't really care why it is happening, only that I observe it and change my listening habits as a result. With this experience, it changes my behavior and I usually turn my amps on a few hours before I plan to listen and then leave the room and have dinner or do something else. I always turn my amps on for a few hours before any critical listening.
You can ask for explanations as often as you like, but I can not provide you with any. Perhaps you should contact Pass Labs.
I think I have been pretty clear about my observations. I never said that I was immune to the power of suggestion, only that I do not think I am hearing the changes with my Pass amps warming up simply because I also read it in a Pass manual. I am not alone in this observation. If you want to continue to press me for proof or suggest that I am asking questions that I am not, you will not get anywhere with me. Sorry.
Other Forum Members,
I think part of the problem in these discussions, and it is certainly one of the aspects that I find so frustrating, is that a few of the science minded members who are posting in this thread are asking for, and sometimes demanding, scientific proof from hobbyists who are not qualified or equipped to provide any. It is becoming tiresome. I think this is why there was so much frustration with Amir in his threads about Harmon. There is a combative tone to the discussion, and quite a few members, it seems, would prefer to spend their time doing something else. Frankly, I don't blame them. I think they simply want to listen to their music on their systems and share observations in forums in the hopes that their experiences may add something to the discussion. If it is no longer fun, people will just tune out and go sailing or something.
People who are actually "science minded" will not be disputing amplifier warm up, as this is readily explainable in terms of known physics, electrical engineering, and, specifically, amplifier design. If they don't happen to know these subject areas they will at least know enough to keep quiet.