Hey there! I have a Squier P bass and want to upgrade the pickups to the Seymour Duncan SBP-3 pickups but it recommends running them through the STC-3M3 or 3M4 circuitry for the best tone. I have read up on this electronics and they are intended for active basses. Not sure how this works? Do I have to buy this circuitry for the pickups to work in my bass?