The Radial ProRMP is a 100% passive Reamper. This means it does not require any external powering. The magic behind the ProRMP's great tone is a custom wound transformer that at once converts the balanced line level source to a hi-z output for your amp while also acting as an electrical isolator to eliminate troublesome ground loops that can often cause buzz and hum in the sound. Plug and play easy to use, the ProRMP connects from the recorder to your amp and effects units and does all the impedance matching for you. Just adjust the level to suit!