Proel D20P Stereo Passive Direct Injection BoxDI Boxes perform several important functions: they are designed for impedance matching and balancing the signal of a guitar, a keyboard or any line level output source, and for injecting directly the signal with very long connections to the XLR microphone inputs of a mixing console. D20P is a STEREO passive direct box with transformers and does not require any external power such as phantom power or batteries to work. The advantage of a transformer is