The Radial J48 Stereo (part R800 3002 00) is a two-channel active direct box, powered by 48 V phantom power, for live touring and studio recording. It converts two unbalanced instrument-level signals - a stereo keyboard, two basses, an acoustic-electric guitar, laptop or drum machine outputs - into balanced mic-level XLR signals for a mixing desk, with 1/4-inch thru outputs to feed on-stage amplifiers. Radial's proprietary switching power supply raises the internal rail voltage so it can handle about 9 volts of input, much more than typical active DIs, giving extra headroom and low distortion with hot keyboards and active instruments. Each channel has an input pad, and the box has 180-degree polarity reverse, a high-pass filter and a ground lift to deal with hum. Radial specifies 20 Hz to 20 kHz response, 109 dB dynamic range, 0.002 percent THD, 220 kilo-ohm input impedance and 600 ohm output impedance. The 14-gauge steel box measures 84 x 127 x 48 mm and weighs 720 g. No batteries are needed, and Radial provides a three-year transferable warranty.