So the bass player in one of the bands shows up without an amp...how do you put him/her directly into the PA? Easy, use an ACTIVE Direct Interface (commonly known as a DI BOX). The Radial J48 DI Box will do just the trick, and allow you to put the bass directly into the PA system. Just be sure that the Phantom Power from your console is ON (the Active DI requires it). There is a simple way to test for Phantom Power, and it is described on the J48 itself. However, you will NOT need the Radial J48 if the bass guitar contains it's own internal preamp. Easiest way to know this is to check whether or not there is a battery compartment on the bass somewhere, or ask the bassist (but he/she may not even know).