Used Radial USB-PRO Stereo USB DI Box for Laptop Audio Playback

The Used Radial USB-PRO Stereo USB DI Box converts digital audio from a laptop or computer into two balanced XLR outputs, giving engineers a clean, ground-isolated signal path from a USB source to a PA system, mixing console, or powered speakers. Featuring a 24-bit DAC, auto-sensing sample rates, and plug-and-play operation with no drivers required, the USB-PRO handles playback duties reliably in both live sound and studio environments.

This pre-owned unit is a strong fit for venues, houses of worship, AV integrators, and touring engineers searching for an affordable stereo USB DI for live sound without sacrificing Radial's signature build quality. It also serves well as a dedicated playback interface for DJs, presenters, and musicians running backing tracks — anyone who needs to buy a used Radial USB-PRO DI box rather than invest in a new unit gets the same professional audio path at a reduced cost.

Radial's book-end chassis and I-beam construction protect the internal circuitry from the abuse of transport and stage use, while the full-bottom no-slip pad provides mechanical isolation and electrical insulation on any surface. The USB-PRO integrates seamlessly with microphone preamplifiers, analog consoles, and digital mixers, and is recognized automatically as a sound card under Windows and macOS — a proven workflow trusted by audio professionals for laptop direct injection.

Key Features of the Radial USB-PRO USB DAC DI Box

• 24-Bit Digital Audio Converter: Delivers high-resolution digital-to-analog conversion so playback audio reaches the PA or console without the fidelity loss typical of consumer-grade laptop outputs.
• Driverless Plug-and-Play Operation: Appears automatically as an available sound card in Windows and macOS audio settings, eliminating setup delays before a show or session.
• Balanced Stereo XLR Outputs: Low-impedance Lo-Z outputs with switchable isolation allow long cable runs to front-of-house consoles without introducing noise or signal degradation.
• Ground Lift Switches: Side-access ground lift eliminates hum and buzz caused by ground loops between the laptop and the house audio system.
• Mono-Sum Switch: Combines the stereo signal to mono for quick phase checking or feeding single-channel playback systems.
• 3.5mm Headphone Monitor Output: Lets engineers verify signal quality and content locally before sending audio to the main system.
• Book-End Chassis with I-Beam Construction: Protects internal components from impact and keeps the PCB stable under the stress of touring.
• Full-Bottom No-Slip Pad: Provides mechanical isolation and electrical insulation when placed on metal racks, stages, or amplifier tops.

Technical Specifications

• Audio Circuit Type: Custom decoder with analog line drive
• USB Compliance: USB 2.0 full speed
• Bit Depth: 24-bit (16-bit capable)
• Sampling Rate: 44.1 kHz / 48 kHz / 96 kHz auto-sensing
• Sound File Compatibility: WDM, MME, CoreAudio, DirectSound
• Software Compatibility: Windows XP / Vista / 7 / 8 and Mac OS
• Frequency Response: 5 Hz – 40 kHz (30 Hz – 18 kHz with isolation)
• Dynamic Range: >90 dB
• Noise Floor: -90 dB
• Maximum Gain: +8 dBu
• Total Harmonic Distortion: 0.01%
• Stereo Separation: 75 dBu
• Output Impedance: 300 Ohm nominal