I am going to be installing a preamp in my Fender 5 string Jazz bass very soon. I am almost definitely going with a Seymour Duncan STC-3M3. What advantages are there with going 18V instead of 9V? Can I just simply wire up another battery in series to do this, or is it more complicated? If it is that easy, how many batteries is the maximum it can handle, or is there really any point in going with more? I have heard some say that you get more headroom at 18V, but exactly what is headroom as it applies to a preamp inside a bass? I'll be installing it to go with my Bart's. I already have a Bart Jazz pup in it for the neck, but am going to go with the 72MV5E (MM style) in the bridge very soon and want to make sure it will do what I want. I have no problem installing extra switches or pots as needed to get it all running to make use of the tri-coil as well as the jazz pup. Any suggestions or opinions on this would be greatly appreciated.