A DI Box allows you to connect a guitar or bass directly to the mixer's input, rather than mic'ing up your guitar or bass amplifier. This technique is often preferred by musicians who require a "clean" sound. The best DI boxes are ACTIVE and require Phantom Power like condenser microphones. They should be connected to XLR mic inputs.

DI Boxes typically have the following features: Impedance matching, Transformer isolation, input attenuation, Low pass filter, Earth lift to prevent 'ground loops' and phase reverse. They are normally powered by a internal battery or by the mixing consoles +48v phantom supply.