-
Modifications to boost bass and balance the top end if you find them a bit harsh. These include swapping out the ear pads, punching holes in the membrane on the back of the driver, altering the grills on the back of the enclosure, sticking blu-tack on the magnet (!), then on to more involved stuff like changing the cable and replacing the plastic cups for wooden ones. Most of it is easy and reversible so you can tune them to your preference.
https://www.headphonesty.com/2018/02/introduction-grado-modifications-ear-cups-driver/
What's in the grado rabbit hole for the uninitiated?