The Whirlwind IMP 2 Passive Single Channel Direct Box for PA or Studio is a rugged built single channel passive direct box. The unit converts a line or instrument level unbalanced signal to a low impedance microphone level balanced signal. Direct boxes are often referred to as DI boxes. This stands for Direct Injection as their main purpose is to convert unbalanced and/or high impedance instrument signals into a format suitable for direct connection to a mixing console - without the use of a microphone.