Passive direct box
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.
(For full specifications see manufacturers product site under "links" tab)