They don't
. The difference that I experience on head, as measured with in-ear mics, with several samples of the K371 and two of the N700NCM2, is larger than what graphs on ear simulator would suggest, for several reasons (not just leakage but coupling in general).
Both of them sound somewhat decent (at least some effort was made to reach a target), but I would not consider them as good platforms to know what the Harman target is supposed to sound like.
A significant advantage the N700NC(M2) holds over the K371 is the use of an active feedback system to - theoretically - deliver a constant FR in the range where it operates regardless of leakage / seal issues, which is something the K371's design is
very susceptible to (more or less so depending on the user's anatomy and the state of the pads).
It isn't quite as robust / sophisticated as what Bose or Apple do, but the response I experience with mines is a lot more consistent than the K371 either with positional variation or between the two channels.
Just as signifiant an advantage your solution has is the Qudelix's PEQ
. The N700NCM2's app EQ, while seemingly giving lots of flexibility, may limit the maximum slope of the correction I believe. I was never able to correct to satisfaction the 800-4kHz range because of it.