The Radial ProDI is a passive mono direct box built around a custom-wound transformer that lets it handle high-output instruments (like active basses, acoustic guitars with onboard preamps, keyboards, and drum machines) without distortion while naturally smoothing harsh transients. It features a very high 140 kΩ input impedance to avoid loading down instrument pickups, and its transformer provides full isolation to eliminate hum and buzz caused by ground loops, with an internal MuMETAL shield to prevent electromagnetic interference. A ‑15 dB pad accommodates hot signals, a ground‑lift switch helps troubleshoot noise, and a thru jack allows feeding a stage amp while sending a clean, balanced XLR signal to the console. Housed in Radial’s rugged 14‑gauge steel “bookend” chassis, the ProDI is durable enough for touring and quiet enough for studio work, offering reliable, plug‑and‑play operation with no power required.