Radial USB-Pro

Stereo USB Direct Box with Balanced Analog Outputs

The Radial USB-Pro is a stereo digital-to-analog direct box that streams balanced analog audio from any USB computer straight into a console, microphone preamp, or live sound system. Plug-and-play behaviour on Mac and Windows means instant recognition—no drivers, no proprietary software. The USB-Pro automatically appears as an external sound card the moment a USB Type-B cable is connected. 24-bit/96 kHz converters and a pair of balanced XLR outputs replace the laptop's noisy headphone socket with a clean, professional-grade feed suitable for stage playback, DJ rigs, corporate presentation audio, and studio transfer sessions.

What sets this direct box apart from generic USB interfaces

A switchable isolation transformer path eliminates the ground-loop hum that ordinary DI designs cannot reach. The single front-panel level knob ranges from fully muted through mic level up to +4 line level, while a built-in headphone amplifier lets the operator verify signal flow before sending audio out to the PA.

Digital conversion and host interface

Bus-powered operation and these converters together define how cleanly computer audio reaches the venue's mixer.

• Converter resolution: 24-bit/96 kHz — retains detail from hi-res playback files and studio reference tracks
• Host connection: USB Type-B, plug-and-play — automatically recognised on Mac and Windows with no driver installation
• Operating current is drawn directly from the USB host, removing one common live-rig point of failure.

Balanced outputs and ground-noise rejection

The XLR stage and isolation circuitry decide whether the signal reaches the console free of computer buzz.

• With 2 channels (left and right) on balanced XLR, you can feed any console, mic preamp, or powered speaker with noise-free runs.
• Switchable isolation transformers: per channel — silence ground loops between laptop power and venue wiring
• Ground lift: per output switch — provides added hum suppression when transformer isolation alone is not enough

Front-panel controls and chassis geometry

Range of levels, headphone monitoring, and a compact housing shape how the unit behaves in live use and travel.

• Level control range: mute through mic level to +4 line level — adapts directly to powered speakers, mic preamps, or studio monitors
• Headphone output: 3.5 mm jack with onboard amplifier — confirms signal is present before live audio reaches the PA
• The chassis is built from 14-gauge steel, with dimensions of 127 × 84 × 51 mm (W × D × H) and a weight of 0.68 kg, fitting crowded racks and packing flat in a gig bag.