(another) Carvin preamp replacement question

OK, I have searched and haven't found specifics (please forgive me and direct me to them if I missed 'em).

I have a 2001 Carvin LB70P. It has piezo's. I am interested in trying out new electronics, pickups, etc.

Can someone direct me to a preamp. I find plenty of info on pickups and such but I haven't been able to locate detailed info on preamps. I like Bartolini - I have passive Barts on a Precision and am happy enough to lean towards Bart preamp, eventually to try some Bart pups.

Is my thinking right? I can't afford to just replace everything all at once so I am thinking: (1)preamp (something that allows for piezos then later on (2)bridge & neck pups ---- for what it's worth bridge is a humbucker. Any info is great especially packages that I can pickup seperately that work well together.

Sorry - this is obviously in the wrong place. MODS, if you could correct my mistake, I would appreciate it.