DI unit

A DI unit is a device typically used in recording studios to connect a high-impedance, line level, unbalanced output signal to a low-impedance, microphone level, balanced input, usually via XLR connector. DIs are frequently used to connect an electric guitar or electric bass to a mixing console's microphone input. The DI performs level matching, balancing, and either active buffering or passive impedance matching/impedance bridging to minimize noise, distortion, and ground loops. DI boxes are extensively used with professional and semi-professional PA systems, professional sound reinforcement systems and in sound recording studios.