On Equalization (EQ)
[Viewing glasses correct for vision imperfections - EQ corrects for hearing imperfections]
1. If you wear viewing glasses, has it ever crossed your mind not to wear them to maintain the “purity” of the image entering your eyes? And so let's get this out of the way first: you'll (still) find people against using EQ. I suggest that their reasons should only apply to you, if you hear something. I've tried for over 30 years to understand what could an EQ do to the music that is bad (I read some theory to do with the phase), and that I can hear, and not one of those against was able to point me to some specific musical examples and what I should hear, and I could never hear anything on my own. And if there ever was anything wrong with the EQs decades ago - the eyeglasses got better in time as well, certainly that’s not the case anymore. Just look at one of those huge mixing desks the pros use. What’s in them? Hundreds of EQ (and other signal altering) circuits.
2. Your hearing is not linear, far from it! Not only that, but it depends heavily on the volume you listen at (search for "loudness"). And so, very surprising to me, most people focus on what the EQ can do to the playback curve of the headphones, completely disregarding their own hearing abilities. Now, using an EQ to simply compensate for your hearing imperfections is, unfortunately, quite hard - I won’t go into details here. But there are a few EQs out there which try to help. One of them is built in some Samsung phones. It is called, at least on my S6, Adapt Sound. It plays tones of various frequencies, separately on your left and right ears - very important!, and it asks you what’s the lowest volume you can still hear. Then it applies the necessary corrections, and a target EQ curve. Here is what it did for me, on my Grado 325e:
Note the significant differences between my ears - and yes, I have a bit of tinnitus.
Have you ever measured what you can hear? Only then you can try to make the appropriate corrections.
And I don't know what target curve Samsung uses, I looked for explanations online but I couldn't find anything. It looks to me that, probably because it's a phone, they favored the midrange. And I don't understand why the final curves are not the quite the same. It might simply be that it’s not a precision tool.
3. Besides what one can hear, objectively, measurably, one's sensitivities - what you care about, are also very important. And many of them can be educated. Besides paying attention when you listen, trying a multitude of headphones, amps, you could even use something like https://www.trainyourears.com/. I haven't done this and so I can't recommend it, but the point is that you can train your hearing.