ATC and Loki

Outside of Fletcher Munson, there is no reason a system should so different within its power bandwidth. I think a lot of the impressions one gets of a system sounding different with level is really related to distortion, power compression or mismatched driver efficiencies. The bass falling off at lower level is obviously Fletcher Munson ear behavior, and inexperienced listeners do not think about this effect when testing systems. Its exactly how a demos can used to make a listener think there is "more bass" on one vs the other by having levels ever so slightly different (say a 1/2dB or so) that you don’t notice the overall level difference, you notice the more bass and to a lesser extent, more highs.

From working with engineers for 30+ years, the good ones, I can tell you from observation and personal experience "critical listening" is a very complex skill that is difficult to master.  Always remember one simple fact: the first sound of any comparison is the reference.

Yes, I think this is more about ears than equipment per se. Mine are not nearly as fine-tuned as most of the people here. By the way, I’ve been playing with my new toy and it’s fun. Where I will end up in terms of settings or usage is still up in the air.

I have definitely noticed most systems have a unique sweet spot in volume, typically not low volume. This isn’t psychological. Some do sound great at low volumes. I am confident that the differences among systems exist. However, I have been fortunate that I have lived in places where I could play at any volume I want… so I never did a systematic investigation. I bet a lot of folks from Europe and Japan have.

I wont deny that it could be proper gain staging that affects the signal chain in some set ups.