The Radial ProAV1 (order no. R800 1112) is a single-channel passive multimedia direct box made for AV rental companies, integrators and live engineers who need to connect almost any audio source to a mixing console. Inputs include a 1/4-inch jack, stereo RCA and 3.5 mm stereo TRS for instruments and -10 dB consumer devices, plus a +4 dB balanced XLR line input with its own select switch for professional sources. Stereo sources are automatically summed to mono to save mixer channels, and the jack and RCA inputs can double as thru-puts, for example to feed an on-stage amp. A high-performance custom-wound Radial transformer, housed in a mu-metal shield, balances the signal, rejects RF and electromagnetic interference, and eliminates ground-loop hum. A -15 dB pad handles hot sources such as CD players and headphone outputs, a ground lift disconnects pin 1 at the output, and the output is a balanced 600-ohm mic-level XLR. It is fully passive and built in a 14-gauge steel book-end enclosure that protects the connectors.