Hi Diablo,
no I'm not a knob twidler either! However in a quest to get maximum ooomph out of my Jazz I hit on this : (from L-R)
Entrance .3, Bass 5 , Frequency 250, Level 5, Frequency 500,Level 5, Treble 4 - I don't have my amp at home , I'm working from a scrap of paper from my kit bag.
When I get a cheap P copy I found that different settings were more effective.( can't remember what they were)
I'll PM the Jazz Bass settings with corrections / updates when I get my amp back.