Switching out Bartolini Pickups - Ibanez BTB

[JFK838]

I have an ibanez BTB bass with two active bartolini soap bar pickups (2 9 volt batteries - overkill in my opinion!), and I guess a stock ibanez pre-amp? I stopped playing it over the last 6 months because I find the tone is way too modern for me - basically only good for slap, which I don't do in any of my bands at this point. I've been borrowing a MIM Fender p-bass and much prefer those junky stock pickups to the bartoloni's at this point.

I was going to get a new bass, or put round wound strings on my ibanez, anything to try and get a fresh, mellower sound of it.

It recentley occured to me I could maybe put some new pickups in it - it's a beautiful instrument, and plays great, I just hate the sound.

Any recommendations, particularly regarding some passive pick-ups that are the same shape that I could put in it, and what I might do about the pre-amp if I put passive pick-ups in this (I assume that might be problamatic - complete noob here, sorry). I am more into a p-bass sound, with a nice thump to it these days... something woody and organic sounding.

Thanks for any help, or leads!