The ProDI from Radial Engineering is a high-quality, single-channel, ultracompact passive direct box designed to handle high-output instruments without distortion. The unit features a custom-made transformer that is able to handle high levels without saturation and has a linear frequency response from 20 Hz to 18.5 kHz, making it ideal for electronic musical instruments and audio equipment. Also featured is a -15 dB pad for high-output sources and ground-lift switch to troubleshoot noise from ground loops. A 14-gauge welded I-beam inner chassis and outer shell greatly reduce the possibility of torque stresses being applied to the PC board. A full-bottom no-slip rubber pad works double-duty by providing protection from electrical shock and making sure the ProDI stays put.