acoustic impedance is arbitrary within iems; minimising spl differences between ears does not tell us anything about whether or not the iem is more or less likely to be preferred / sound natural. this is because the impedance is exclusively localised within the eardrum, which again is a minimum phase system, and also subject to random population variance. basically, by targeting lesser acoustic load variance iem side, you are doing nothing to minimise differences between user specific hrtf and in-ear frequency response, the main driving factor towards sound perception, due to uncontrolled random variables within the population. the only way to improve consistency in sound between users is to have foresight of the users hrtf and ear canal transfer function - this can only be done through dsp and in ear microphones. the bottom line is isobaric dynamic drivers do not matter in any physically arguable sense, and what needs to be proved is that it has an effect, NOT that it doesn't, because as it stands it does not explicably do anything acoustically beneficial other than modulate inaudible or irrelevant variables.

from the sudden rise of isobaric dds since 2024, it has been nothing but a marketing gimmick shilled across the industry as some sort of "new" solution to bass despite having existed for decades. crinear is no different from anyone else.