Pro-Ject DAC Box S2+ silver

The Pro-Ject DAC Box S2+ concentrates within a compact format the digital-to-analog conversion technologies developed for far more expensive devices. Equipped with the ESS Sabre ESS9038Q2M converter, this DAC supports PCM files up to 32-bit/768 kHz and DSD256 decoding, while offering five digital filters to tailor the sound signature to your preferences. With jitter measured at 100 femtoseconds and dual USB filtering, this converter is aimed at those seeking faithful reproduction of their digital sources without compromising on size.

A compact enclosure that protects the essentials

The DAC Box S2+ features an aluminum and metal chassis measuring 103 × 37 × 122 mm and weighing 355 grams. This sandwich construction protects the internal circuits from vibrations and electromagnetic interference. The front panel has only two push buttons: one to select the input source, the other to choose among the six digital filters. No superfluous display, no ornamentation: the design reflects Pro-Ject’s functional approach. Manufactured in the Czech Republic, it is available in natural brushed aluminum or matte black.

The ESS Sabre ESS9038Q2M converter and its proprietary clock circuit

At the heart of the DAC Box S2+ is the ESS Sabre ESS9038Q2M converter, a 32-bit chip derived from the ES9038PRO circuit used in professional equipment. The ESS9038Q2M retains the HyperStream II architecture and time-domain jitter eliminator that built the reputation of ESS converters, achieving a dynamic range of 120 dB and a total harmonic distortion rate of 0.0007%.

Pro-Ject complements this converter with a proprietary clock circuit that synchronizes all internal oscillators, reducing jitter to 100 femtoseconds. This timing precision, usually reserved for far more expensive dedicated clock generators, places this compact converter among the benchmarks in its class. The four-layer gold-plated printed circuit board minimizes signal path lengths, while organic polymer capacitors and thin-film miniMELF resistors ensure stability and low distortion.

Six digital filters to shape the sound

The DAC Box S2+ offers five standard digital filters from the ESS chip, plus a sixth proprietary filter: Optimum Transient. Each filter applies a different trade-off between cutoff speed, phase, and transient behavior. The five ESS filters include linear-phase options with fast or slow roll-off, minimum-phase filters, as well as a brick-wall filter.

The Optimum Transient filter, developed specifically by Pro-Ject, focuses on the reproduction of transients—those wavefronts that define the attack of instruments. When switching to very high sampling frequencies, a stabilization time of around three minutes may be required, a behavior linked to the ESS chip itself. Filter selection is done directly from the front panel, allowing you to adapt the sound signature according to the type of music, system characteristics, or personal preferences.

Three digital inputs for all your sources

The rear panel houses three input connectors. The type-B USB, based on XMOS asynchronous technology, accepts PCM files up to 32-bit/768 kHz and DSD streams up to DSD256. This input uses both active and passive filtering to eliminate noise carried over this type of connection, with attenuation up to 75 dB at 1 kHz.

The coaxial S/PDIF and optical TOSLink inputs, limited to 24-bit/192 kHz, are sufficient to connect a CD transport, network player, TV, or any device equipped with a standard digital output. The stereo analog RCA output delivers 2 Vrms, a standard value compatible with amplifiers and preamplifiers. Power is supplied via the included external 5 V/1 A adapter. When the USB input carries the audio signal, the DAC can be powered directly from the computer, although Pro-Ject recommends using the external power supply to avoid interference.

Certifications and compatibility

The DAC Box S2+ is Hi-Res Audio certified by the Japan Audio Society and carries the Roon Tested label, ensuring optimal compatibility with this music management software. For Windows, a dedicated driver is required (provided and available for download). macOS systems recognize the DAC natively, with no additional installation needed.

The compact format of the DAC Box S2+ allows for a variety of setups: on a desk, in a traditional hi-fi system, or in a home theater installation. Its 103 mm width makes it possible to stack it with other components from the Box Design range, creating a modular system where each element can be chosen according to specific needs.

Technical specifications

Digital-to-analog conversion

• High-end ESS Sabre ESS9038Q2M digital audio converter
• PCM playback up to 32-bit / 768 kHz
• DSD64, DSD128, DSD256 decoding (DoP)
• Proprietary clock with full internal synchronization
• Ultra-low jitter: 100 femtoseconds
• 4-layer gold-plated printed circuit board
• USB interface with double filtering to eliminate parasitic noise
• Digital filters: 5 front-selectable profiles + 1 proprietary “Optimum Transient” filter

Connectivity

• Digital inputs
  • 1 × asynchronous USB-B
    • PCM up to 32-bit / 768 kHz
    • DSD up to DSD256
  • 1 × RCA coaxial (S/PDIF)
    • PCM up to 24-bit / 192 kHz
  • 1 × TOSLink optical
    • PCM up to 24-bit / 192 kHz
• Analog output
  • 1 × stereo RCA

Audio performance

• Frequency response: 20 Hz – 20 kHz
• Total harmonic distortion: 0.0007% (0 dB, 2 V RMS, 1 kHz)
• Dynamic range: 120 dB

Construction and components

• Aluminum / anti-vibration metal chassis (silver or black)
• Audiophile-grade components
  • Organic polymer capacitors
  • Thin-film miniMELF resistors

Power supply

• External 5 V / 1 A DC power adapter (included)

Dimensions and weight

• Dimensions: 103 × 37 × 122 mm (W × H × D, including knob and connectors)
• Weight: 355 g (without power adapter)