I can't seem to do it, I ended up with something like this for my £20 earphones after several hours of playing with it:
https://imgur.com/wWBpIQE
I listened to music but it sounds very muffled, so do voices.
I basically used this:
https://www.szynalski.com/tone-generator/
and basically either boosted or lowered the Hzs that sounded too high/low.
Is there just some device I could buy or something? I don't think I'm good at this at all; it would help a lot if I had some sort of point of reference, but I've never heard music with a neutral EQ, never been to a concert either.
Oh perhaps you have an EQ profile for cheap earphones that I could try and see if they work for my ones?