I had the chance to borrow a pair and here’s my preset! Put the bands in order for max quality. Designed for maximum iOS 14.

Lowshelf from 20 hz with -10 dB ;

Lowshelf from 40 hz with +1 dB ;

Lowshelf from 80 hz with +1 dB ;

Lowshelf from 400 hz with +1 dB ;

Lowshelf from 500 hz with +1 dB ;

Lowshelf from 4500 hz with -10 dB ;

Lowshelf from 5000 hz with -1 dB ;

Lowshelf from 5500 hz with -1 dB .

PS: I took inspiration from Apple’s eq in built-in speakers in iOS 15, to not forget to amplify the Booms! (below 100 hz) . (I don’t know a jailbreak yet for iOS 15 :/ )