Small boxes usually come with big compromises. The Pre Box S3 mostly ignores that rule. Built by Pro-Ject Audio Systems, this compact stereo preamplifier is designed to sit comfortably on a desk yet function confidently as the control center for a system. It handles analog, digital, and wireless sources, works as a preamplifier, headphone amplifier, and DAC, and is flexible enough for an office setup or a slimmed-down main rig where rack furniture isn’t invited. Pricing is set at $699 (£499 / €599), positioning the Pre Box S3 as a mid-priced option for a compact preamplifier that also covers DAC and headphone duties in one unit.
The idea is simple and refreshingly grown-up: source switching and volume control handled in one tidy box, with enough connectivity to cover turntables, TVs, streamers, laptops, CD players, and headphones without drama. Pro-Ject claims 13 inputs and outputs in total, which sounds like marketing bravado until you realize it actually adds up. Pair it with active speakers or a compact power amp, and you’ve got a modern hub that keeps things small, clean, and functional—without feeling like a compromise system you’ll want to “upgrade away from” in six months.
Pro-Ject Pre Box S3: A Compact Hub for Modern Audio Systems
This is a do-it-right, don’t-show-off design. The analogue stage uses short, low-noise signal paths, and the digital and analogue sections are kept properly isolated. A 24-bit/192kHz DAC with accurate clocking handles digital sources, keeping noise and timing errors under control. The result is neutral, consistent playback that reflects the source rather than imposing a sound of its own.
Connectivity is practical rather than flashy. Two RCA line-level inputs sit alongside coaxial and optical digital inputs, plus HDMI eARC for TV audio. A dedicated subwoofer output allows proper low-frequency integration in compact systems. There’s a built-in moving magnet phono stage with 45dB of gain, so turntables can plug straight in, and USB-C support covers laptops and modern mobile devices without adapters. Headphones are handled via a 6.3mm jack rated for 16–600 ohms (2 x 70mW at 32 ohms), or wirelessly over Bluetooth 5.0 with aptX HD, capped at 24-bit/48kHz.
The analog outputs can operate in variable mode for power amplifiers or fixed mode for secondary systems, and RS232 support allows integration into custom or multi-room installations. Digital conversion is handled by a Cirrus Logic CS4344 DAC with support for PCM up to 24-bit/192kHz. Streaming and file playback are strictly PCM-based. There is no support for MQA or DSD, and Bluetooth stops at aptX HD—no aptX Lossless or LDAC.
Power is supplied via an external 18V/500mA DC adapter with universal 100–240V, 50/60Hz compatibility, and standby power consumption remains below 0.5 watts. RS232 connectivity is provided via a pluggable 3-pin terminal block for custom installation or multi-room control. The chassis measures 206 × 55 × 153 mm (176 mm without sockets), which translates to 8.1 × 2.2 × 6.0 inches (6.9 inches deep without sockets), and the unit weighs 1,020 grams (2.25 pounds) without the power supply.
The Bottom Line
The Pro-Ject Pre Box S3 is a compact control center that focuses on doing the essentials properly. It combines a preamplifier, DAC, headphone amplifier, moving magnet phono stage, HDMI eARC, and Bluetooth in a desktop-friendly chassis, with enough connectivity to anchor a small office system or a space-conscious main rig. Digital support is limited to PCM up to 24-bit/192kHz, with no MQA, DSD, or advanced Bluetooth codecs beyond aptX HD, so expectations should be set accordingly.
Designed as a natural partner for Pro-Ject’s Amp Box S3 or Amp Box DS2 when more power is required, it also works just as well with other power amplifiers or active speakers.
For more information: project-audio.com
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