Replace preamp and/or pickup in Stingray 4???

[Philthy]

I presently own a Stingray 4 w/ maple fret board (I believe it's about 2 - 3 years old). I love stingrays and their feel. However, I'm contemplating changing the on board preamp to get better, tighter, smoother, punchier lows while keeping decent highs and treble. My stock preamp seems to be very noisey and buzzy. When I touch the strings or bridge, it stops. However, I've read somewhere that it could be normal because of the stingray pickup. Anyway, has anyone out there changed the preamp? Any suggestions or advice? Would the stock pickup sound good with a new preamp or do I have to change both the pickup and preamp? Any advice, recommendations or suggestions would be greatly appreciated. Thanks!!!

(if it makes a difference, my present rig is a SWR Bass 750 w/ Goliath III & Son of Bertha cabs)