As for linearity, its value is greatly exaggerated. There is absolutely no need to make the linearity of the system with an accuracy of 0.3 db, much less 0.1 db. If it was so important for perception, we would not be able to enjoy listening to cassette recorders, receivers, and so on. By our nature we automatically adapt to changes in the frequency response within a wide range, this is how our perception works. Adaptation to changes takes a few tens of seconds, after that we get used to the new reality and the new frequency response becomes "transparent" for us, it does not interfere and does not help us to perceive music, it just becomes a kind of reference point, relative to which we perceive sounds..Very important point to meditate.....
This statement is easy to verify, if you have timbre controls in the system, turn the controls a bit, spend 10 minutes listening calmly and analyzing impressions, make a conclusion.
The CORRELATIONS for example between physical acoustic and psychoacoustic are anything except linear...It is deeply non linear...
Personaly i think that there is an unknown participation of the consciousness to the phenomena that we miss "systematically" in viewing the object always separated of the subject or in an "external" relation only...

