I mean the acoustic signal matching the electrical signal.Don’t know what you mean by output SPL matching input’s signal.
(Aka zero distortion)
^100%^.Some researchers have concluded that an exponential decay of harmonics staring with 2nd harmonic is the least offensive of all patterns because it “hides” in our perceptual blind spots.
I have heard exponential as well.
And I have also heard only 2nd and 3rd, with the second harmonic being “exponentially higher” than the 3rd… with no 4th etc being present.
Even with just 2nd and 3rd though, our ear are much better at spatially locating those wavelengths than it is for the fundamental.
And a higher level of 2nd and 3rd would seem to be more localizable than a ilower level of second and third.
And Oone of ^those^ may be preferred over zero distortion?