Radial PZDI 1-channel Passive Piezo-Optimized Direct Box "Optimized for orchestral instruments on a live stage Adjustable load for piezo and magnetic pickups Variable low-cut filter to control bass resonance 48V phantom powered, does not require batteries" Adjustable load for piezo and magnetic pickups Variable low-cut filter to control bass resonance "48V phantom powered, does not require batteries" The 220k-ohm setting warms up the tone of a magnetic pickup to give you the feel and tone as if connected to a tube amplifier