Pro-Ject DAC Box S2+ black

The Pro-Ject DAC Box S2+ concentrates, in a compact format, the digital-to-analog conversion technologies developed for much 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 double USB filtering, this converter is aimed at those seeking faithful reproduction of their digital sources without compromising on size.

A compact housing that protects what matters

The DAC Box S2+ uses 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 from the six digital filters. No unnecessary display, no ornamentation: the design reflects Pro-Ject’s functional approach. Made 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 uses the HyperStream II architecture and the time-domain jitter eliminator that have built ESS converters’ reputation, delivering a dynamic range of 120 dB and a total harmonic distortion rate of 0.0007%.

Pro-Ject pairs 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, along with a sixth proprietary filter: Optimum Transient. Each filter applies a different compromise between cutoff speed, phase, and transient behavior. The five ESS filters include linear-phase filters 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 reproducing transients – the wavefronts that define the attack of instruments. When switching to very high sampling frequencies, a stabilization time of around three minutes may be required, due to the ESS chip itself. Filter selection is done directly on the front panel, allowing you to adapt the sound signature to the type of music, system characteristics, or personal preferences.

Three digital inputs for all your sources

The rear panel features three input connectors. The type B USB, based on XMOS technology in asynchronous mode, accepts PCM files up to 32-bit/768 kHz and DSD streams up to DSD256. This input uses both active and passive double filtering to eliminate noise carried by 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 for connecting a CD transport, network player, TV, or any device 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 an included external 5 V/1 A adapter. When the USB input carries the audio signal, the DAC can be powered directly by 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 bears the Roon Tested label, ensuring optimal compatibility with this music management software. For Windows, a dedicated driver is required (provided and downloadable). macOS systems recognize the DAC natively, with no additional installation needed.

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

Technical specifications

Digital-to-analog conversion

• High-end ESS Sabre ESS9038Q2M DAC
• 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 PCB
• USB interface with dual filtering for elimination of 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

Build and components

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

Power supply

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

Dimensions and weight

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