Adding electronics to a passive J bass

[Mottlefeeder]

I am interested in adding an on-board preamp to a Corvette, and most of the circuits I have seen fall into one of two camps.

a.) An active circuit coming between the pick-up and the pots

b.) An active circuit coming after all the pots

What difference does it make to the sound of a passive pick-up if you feed it into a hi-z buffer instead of the track of a 250K pot?

Edited January 10, 2008 by Mottlefeeder