slope = rise / run

 

Here it is for that deck, 1=6db, 2=12db, 3=18db, 4=24db. 1 is the weakest "slope" and will let more bass come through your mids and 4 is the strongest cutting off those bass frequencies the quickest. Use your ears to tell you which one is right for you, when in doubt use 2!

 

VERY good Mr steve!!!! a scienterrific answer!