Wow, you people are really dedicated to EQ'ing. Enjoy yourselves.
After trying two analog EQ's in '77 and '78 I swore off - because they was audible and the freqs were not adjustable. Then 42 years later I got into TIDAL MQA/UAPP, and then tried Toneboosters EQ. I did discover while the measuring capability of cans is improving - but the recommended settings (using user popularity - specially under 100 Hz are ludicrous).
I built dedicated sound rooms first for myself, then for others (paid) and unless you try very hard and spend some real money no speaker is going to work near its max capability in a given room. Headphones are quite the same. HFM IMO spend a lot of effort on the drivers but the rest of the package is below average. Did the designer specify crap outside of his design. No, they lived with what corporate/finance dictated. The other day a guy argued that cans are just as the designer planned. Please. Then of course unit-to-unit variability Music played, differences in human hearing.
But jeez that's complicated, let's just pretend they built this can just for me, my system, my tastes, my hearing, my associated equipment.
I am most invested so far with cans in listening, evaluating, modifying of my HFM HE-500. I recommend on this site quite a few times, in order:
1. stock silver plate cable? get/build an OFC cable. Upgrade to XLR if amp works better with it.
2. stock pads are meh, leather angled better, Dan Clark Ether Angled lambskin best - $80
3. replace rear screens with more open mesh, or no screen,
4. install fuzzor mod = most important mod, but as removing takes patience, list it here.
5. on amps that don't control bass and yet deliver impact there are few issues in the bass. Otherwise the "Q" can be too high/sloppy. Most notable with bass guitar with other bass instruments playing at same time. Dynamat on the outer ring of the backside does it.
6. EQ - digital parametric 10 band. This is FR domain only. It cannot give the expansive wide headspace from the pads, it cannot cut the early reflections and cancellation that the fuzzor does. EQ cannot cut the stuffy closed in sound with the stock mesh. Bass can be one note and sloppy without Dynamat - no cure from EQ.
So, after one improves the environment the drivers work in, then the EQ. Complete make over? Not needed. Compared to other cans I have EQ'd - they do not sound the same. Cuts fatigue. allows one to listen into the music easier and better.