You can adjust the pick attack trim pot inside the cavity. I have it set to about 25% or so. 100% is much too harsh and bright for me.
As for the filter knobs: I mostly play without them pulled up. For slap try: Neck: 10, bridge: 5. Blend in the middle (or to taste). Pick attack with 25%. Or without pick attack.
I'm going to pop the back open in the morning ... is the pick attack set at 100% from the factory then? because yes, it's extremely harsh..