The Radial J48 is a mono active DI box for connecting instruments to a mixing console or microphone preamp. It runs on 48 V phantom power and provides a 6.35 mm instrument input, a thru connection for an amplifier and a balanced XLR mic-level output. A -15 dB pad accommodates hotter signals, while the 80 Hz low-cut filter, polarity reverse and ground lift help adapt the signal to the setup. The Merge switch turns the input and thru sockets into two inputs summed to one mono output; it does not provide two independent DI channels.