So here is hopefully my last eq attempt.
This was adjusted by ear, rather than relying on some measurements found on the net.
And below, explanations of the parts of curve.
Boost in 1300 - 2500 hz region: put vocals more forward , make them more euphonic
Large drop after 2500 hz : reduce sibilance
Cavity after 10 khz: treble is reduced, more relaxing
Below 150 hz: boosting sub bass
With this eq, the recording "Point de suture" from Mylene Farmer sounds much less sibilant, and more euphonic .
Works with other stuff too.
It's not so easy to eq the hd800, because you mess up either the clean sound or tightness of bass.
I tried to preserve both ( clean sound & tight bass) , by adopting a solution , that combine minimum phase & linear phase eq-ing.