Barely used Radial JDI Passive Direct Box that never left my smoke-free home. Below is the official description for the item:

World's Finest DI

The JDI is a high performance passive direct box for live concert touring and professional studio recording applications, featuring a premium Jensen transformer for exceptional audio performance.

Pure Sound of the Instrument

The Radial JDI is a passive direct box designed to handle extreme signal levels without distortion of any kind. At the heart, the Radial JDI employs the world class Jensen JT-DB-EPC audio transformer delivering a smooth, warm sounding Bessel curve, reminiscent of the finest vintage gear. Ruler flat from 10Hz to 40kHz and with virtually zero phase deviation, the JDI delivers the natural, pure sound of the instrument without artifact. By its no-power passive design, the Radial JDI performs both high-to-low impedance conversion and signal balancing over a magnetic bridge that passes signal while rejecting stray DC voltage. This makes the JDI particularly adept at eliminating hum and buzz caused by ground loops.

Jensen transformer for optimum performance

The JDI's Jensen transformer is the product of decades of experience in transformer production. This transformer delivers optimum audio performance offering outstanding linearity at all frequencies, combined with extraordinary level handling without introducing distortion.

The input panel features a 1/4" instrument input and traditional thru-put. An innovative 'merge' function allows the thru-put to be converted to a second input to allow stereo to mono summing. This is often used to interface stereo sources such as keyboards or CD players in live shows where audio channels may be not always be plentiful. The JDI also sports a -15dB pad to interface with higher output levels.

The JDI's output panel features balanced 600-ohm XLR connector with pin-2 hot following the AES specification. A polarity reverse switch toggles pin-2 and pin-3 to allow the JDI to interface with older non-AES equipment and for creative tinkering. The ground lift switch disconnects the XLR pin-1 ground from the JDI for 100% input-to-output isolation.

Finally, a second -30dB pad may be engaged that, when used in tandem with the -15dB input pad, allows the JDI to be connected in parallel with a speaker. This, for instance, allows the engineer to 'tap' the sound coming from a guitar amplifier speaker 'post distortion' thus adding another creative dimension. This unique function incorporates a speaker emulation filter circuit that rolls off highs and lows to more closely approximate the sound of a 12" driver.

Construction

As with all Radial direct box, the Radial JDI is designed for use in abusive environments such as on fast-paced stages of concert touring. An innovative book-end design provides a protective zone around the switches and connectors that makes it practically impossible to damage these components.

The inner skeletal frame features a unique 14-gauge welded I-beam construction that makes it impossible to torque the PC board. Stress on the printed circuit board can introduce intermittent solder joints, which by all accounts is the primary cause of direct box failure.

An innovative full-bottom no-slip rubberized pad works double duty by assuring the J48 won't slip and slide around when placed on an amplifier. The protective pad also ads an element of electrical shock resistance by providing a mechanical shield from guitar amp handles that are often directly coupled to the amp chassis.