The heart of the ProDI is a custom wound Radial transformer. It features an exceptionally high 140kΩ input impedance to reduce loading while enabling the ProDI to handle extreme signal levels at all frequencies without distortion. This is further improved upon with an internal MuMETAL® shield to protect against electromagnetic fields that can cause unshielded transformers to distort. The ProDI works great for high output devices like active bass guitars. It's able to handle the huge signal levels from active pickups without distortion and the transformer isolation prevents ground loop hum. The ProDI sends the pure sound of the bass to the PA and to the player's amp. Acoustic guitars can sometimes have sharp sounding active preamps. The ProDI naturally smoothes out the transients for a warmer tone. And because the ProDI is able to handle loud signals from active pickups, it will not distort. This makes it a great direct box for acoustic guitars. Today's digital keyboards are not only very dynamic, they also have a tremendous range from low to high notes. The ProDI is able to withstand excessive signal levels at all frequencies without introducing distortion or phase shift, so all your patches sound great.