So right now I have two basses, a MIM P, and a MIA J, and I like them both for their own respective tones, I like my P-Bass for the punk and reggae I play, and the J for the funk and ska stuff I play. How do I go about keeping my signature sound, even when switching basses, but still retaining the "p-bass sound" and the "j-bass" sound. For instance, Geddy Lee's used Rickenbackers and Jazz basses, but yet when you listen to him, you can still tell that it's Geddy... How does he still keep his voice, even though he's playing distinctly different sounding basses?

His hands.

His hands.

+1...

Everyone has a different style of things like, attack, left-hand muting, right-hand muting, use of hammer-ons, pull-offs, bends, use of accents, use of ghost notes...the list goes on...and the associated timing between all of these elements is also key...

It's especially noticeable on Guy's like Geddy, Les Claypool, Victor, Pattitucci (to name a few)...because they have some aspects of their style that really is signature in their sound.

Different types basses being played by the same person, WILL sound tonally different, but there is much more difference IMO with the SAME bass amongst different players.