The PDI-1 is a DI (Direct Injection) box that allows sound engineers to use the output of any instrument signal with the pre-amps in their mixers, all in a durable tour-grade form factor. Featuring all the typical functions you would expect from a DI box; A 1/4" Instrument level input to accept the signal from your guitar, bass, or other high-z equipment; A Balanced XLR output to go straight to your mixer which also includes A Ground Lift function to avoid the dreaded ground loop hum; and a 20dB Pad for those really hot signals.