The Radial Pro48 incorporates a digitally controlled switching power supply that steps up the rail voltage from the typical 1 volt to an astounding 9 volts! Radial Chief Engineer Denis Rozon comments: "Today, most instruments such as acoustic guitars and basses are equipped with internal preamps called buffers. These can develop anywhere from 3 volts to 6 volts when turned up and played hard. This excessive output level overloads typical direct boxes as they are unable to handle the signal due to the limitations of phantom powering. We developed a work-around in the J48 by using the same trick that power amplifier companies now use to increase the efficiency of their amps. It is called digital switching. Essentially, we take phantom power and convert the high voltage and low current from DC into AC using a special transformer and digital timing chip. We then filter the power and reconvert it to DC to get our 9 volt rails. High rail voltage means more signal handling and less distortion. With demanding customers like Bruce Springsteen and Jerry Douglas using the Radial J48 on their guitars, you can be sure the sound is right."