how does the distance between the strings and the pickup affect the tone. i want to lower the pickups on my bass a bit because the strings tend to hit them but i dont want to mess up the tone.
Reduces the volume for the strings on the side you lower. Not that big a deal. Lower em, and if you dont like it for some odd reason, raise em back.

However, I'd think that the strings hitting the pickup would be quite an issue with having good tone...