As any touring musician will tell you, bringing your own DI box to a gig is essential. A DI Box simply isolates your mixer, homemade electronic synth, or circuit bent device audio signal from the PA system that really really wants to amplify it. It’s function is to eliminate impedence mis-matching and ground loops which often cause high noise, 60 Hz hum, and loss of fidelity. The signal path hot tip wire from the 1/4 inch jack is isolated by a transformer from the XLR output as well as the ground in the Ground Lift mode.
In my experience this particular DI box by Live Wire Solutions does a nice job of controlling the noise while being a great interface between your gear and the “sound guy” running the PA system.
The DI can be purchased from a local Guitar Center for about $40. As you can see there is not a whole lot to it. However just in parts it seems like a great deal.