Pro-Ject Pre Box S3 – Compact Stereo Preamplifier with Phono, DAC and HDMI eARC

For decades, Pro-Ject Audio Systems has focused on creating space-efficient HiFi components that fit naturally into modern living environments without compromising functionality. Compact preamplifiers have become a key element in this philosophy, especially as today’s stereo systems increasingly combine analogue sources, digital playback and TV audio. With the Pro-Ject Pre Box S3, the company expands its Box Design Series with a model intended to act as a comprehensive control center for contemporary stereo systems.

Key Facts

• Compact stereo preamplifier with extensive analogue and digital connectivity
• Integrated MM phono stage, DAC and dedicated headphone amplifier
• HDMI input with eARC and HDMI CEC for direct TV integration
• Analogue volume control using a motor-driven potentiometer
• Designed for use with active loudspeakers, power amplifiers and subwoofers
• Custom installation support via 12 V trigger and RS232 interface
• Developed and manufactured in Europe

A compact control center for analogue and digital sources

The Pro-Ject Pre Box S3 is conceived as a universal hub that brings together a wide range of playback devices. Two analogue line inputs are complemented by an integrated moving-magnet phono stage offering 45 dB of gain, allowing turntables to be connected directly without the need for an external phono preamplifier. This makes the unit particularly appealing for users who consider vinyl a permanent part of their listening routine while keeping the system footprint compact.

On the digital side, the Pre Box S3 offers coaxial and optical S/PDIF inputs, an asynchronous USB C interface and Bluetooth 5.0 with aptX and aptX HD support. A dedicated HDMI input with eARC and HDMI CEC extends its role beyond traditional HiFi, enabling straightforward integration of a television into a stereo setup. In everyday use, this allows TV sound to be routed through active speakers or external power amplifiers without additional converters.

Digital processing and DAC architecture

At the heart of the digital section is a Cirrus Logic CS4344 digital-to-analogue converter, capable of processing signals up to 24 Bit and 192 kHz. Pro-Ject Audio Systems employs a dual-mono layout to maintain stable signal paths and consistent channel separation. From a practical perspective, this approach supports scenarios where multiple digital sources such as a CD transport, network streamer and TV are connected simultaneously, all handled by a single central component.

Analogue volume control and headphone amplification

Volume adjustment is handled entirely in the analogue domain via a motor-driven potentiometer. This design enables precise level control while allowing convenient operation via remote control, without altering the signal digitally. In addition, the Pre Box S3 features an integrated headphone amplifier capable of driving headphones with impedances ranging from 16 to 600 Ohm, making it suitable for both efficient models and more demanding designs.

Outputs and system integration

For system integration, the Pre Box S3 provides a variable Cinch output intended for power amplifiers or active loudspeakers, along with a fixed line output and a dedicated subwoofer output. This flexibility supports classic stereo systems as well as configurations that include a subwoofer or a secondary listening zone. Custom installation environments are addressed through a 12 V trigger output and an RS232 interface, allowing the preamplifier to be incorporated into more complex control systems.

Design and enclosure

Consistent with the S3 Series, the Pre Box S3 is housed in a compact aluminium chassis that serves both aesthetic and functional purposes, including shielding against external interference. Available in silver or black, it is designed to integrate discreetly into HiFi racks, desktop audio systems or living-room installations.

Price and availability

The Pro-Ject Pre Box S3 is available now through authorised retailers. The recommended retail price is € 599,- including value-added tax.

Conclusion

With the Pre Box S3, Pro-Ject Audio Systems addresses users seeking a compact yet comprehensive control unit for modern stereo systems. By combining phono preamplification, digital conversion, TV integration via HDMI eARC and headphone amplification in a single device, it covers a wide range of everyday use cases. Its focus on flexible connectivity and system integration makes it a practical choice for both minimalist HiFi setups and more advanced stereo installations.

Technical Specifications