Pro-Ject Pre Box S2 Review: This Digital DAC is a little miracle

The “vinyl renaissance” that we have seen in recent years does not mean that everyone suddenly became fans of the old – well, time-tested – technology, resigned to its inconveniences and shortcomings and does not want to hear about digital audio. On the contrary, it is gaining momentum, offering ever higher sound quality while further reducing the cost and increasing the comfort of use. It is not for nothing that such a luminary of analog sound, like the Pro-Ject company, has an extensive family of digital devices in its range of products.

This family includes six lines of electronic components in small and very tiny packages. The Pro-Ject Pre Box S2 Digital DAC belongs to the second category, and the S2 series occupies the middle position in it – there are devices that are both cheaper and more expensive. It includes two dozen models, from which you can make up a versatile full-fledged Hi-Fi system that can fit on the edge of a table or in a corner on a shelf.

However, you can limit yourself to one Pre Box S2 Digital, in order to listen to music with high quality and with pleasure – it is enough to get good active speakers and / or headphones, but a personal computer has already become an indispensable attribute of modern life. This unit functions as an external USB DAC, preamplifier and headphone amplifier. It also has a pair of SPDIF inputs, which allows it to be used with more traditional Hi-Fi digital sources. A small but handy remote control will be useful in this case.

In this representative of the S2 line, for the first time, a “dual mono” circuitry was used for it, based on two high-quality 32-bit ESS Saber ESS9038Q2M digital-to-analog conversion chips. This provided it with compatibility and processing of PCM streams with parameters up to 32 bit / 768 kHz and DSD up to DSD512 on the USB input. He also has hardware support for the MQA format.

The company, renowned for its vinyl turntables, also boasts its own digital technology. In particular, in the Pre Box S2 Digital, in addition to seven digital filters “included in the package” with the DAC chips, the Transient Optimum developed by Pro-Ject is used, as well as the proprietary clock pulse generator circuit, which made it possible to achieve such a minimum jitter that many competitors can envy. “Digital audio is the art of managing time,” says the company’s website.

The entire stuffing of the multifunctional device was able to fit into a tiny case, among other things, thanks to the use of organic polymer capacitors and thin-film mini-resistors on a four-layer PCB with gold-plated tracks.

Small component in a large hi-fi system

Electronic Components Pro-Ject Pre Box S2 Digital
The device is powered in two ways: using a complete network adapter if the content source is connected via a coaxial or optical input, and if a USB connection to a PC is used, then it will be enough to power the DAC. In this case, it is strongly recommended to disconnect the adapter.

Since the Pro-Ject Pre Box S2 Digital has volume control, it can be a partner of active speakers in a minimalist system. During testing, we tried to check how high-quality signal it is capable of providing them, so we connected this DAC to very expensive and serious components, which, of course, are not a match for it, but they certainly will not spoil anything, but will only fully demonstrate its capabilities.

These are the Yamaha C-5000 / M-5000 two-component amplifier   and Revel F-52 floor standing speakers. The digital stream was initially fed to the coaxial DAC input from a Technics SL-G700 network player .

DAC Pre Box S2 Digital managed to prove itself in the most worthy way. It has a balanced, detailed, dynamic sound with deep bass and excellent focus. Beethoven’s Fifth Symphony performed by the orchestra conducted by T. Currentzis is presented informative and expressive.

The stage is large-scale and well-structured, with no cramped instruments. This expressive interpretation of the famous piece is full of sudden large-scale dynamic shifts, and it is very important that the flow of the music “does not slow down”, and that the quiet fragments are no less clear than the loudest ones.

With all of this, the Pro-Ject DAC copes well, providing a thoughtful yet emotional listening experience. It can only be noted that in comparison with more expensive competitors, for example DAC RME ADI-2 DAC FS, the sound is somewhat lacking in timbre saturation and sophistication, and, consequently, naturalness.

The DAC is housed in a two-layer metal case, with a 6.3mm headphone output, volume knob and other controls on the front aluminum panel, and a small display. However, some settings are available with the remote control.

Target application

A more targeted application of this device – with a personal computer – was implemented using the Intel NUC8I5BEH mini-PC, which has approximately the same dimensions as the DAC from the Pro-Ject S2 line. As a rule, in this case, the choice of the software player has a big impact on the sound quality; our content source had perhaps the best one to date – Roon. Its software core Roon Core is installed on the NUC, and the component we are testing has in the description the Roon Tested mark.

Muse’s songs from the Black Holes and Revelations album , available on Tidal, sound better over USB than coax with the Technics SL-G700. The scene turns out to be deeper and more organized with better elaboration of all the details and nuances of multifaceted and rich compositions.

Deep, rhythmic bass lines are more controllable and contain more texture. The vocals take their proper place on this musical canvas and appear more lively and expressive. And if you choose the same recording in MQA format, then the sound quality will receive an additional increase in all aspects. However, the aforementioned competitor from RME shows more talent even with USB connection.

In the Oppo PM-3 headphones, the sound has a similar character, except that the acoustic space above your head does not differ in scale, and the presentation is generally more meager and restrained. However, even this way of listening provides a non-tiring and emotional perception of music of various genres. It is also worth experimenting with digital filters – the difference is small, but the shades that they give to the sound will allow you to adjust it to your taste.

Rear panel of Pro-Ject Pre Box S2 Digital
There was hardly anything else to fit on the back panel.


For its size and price, the Pro-Ject Pre Box S2 Digital DAC is very good. It performs as many functions as its small body allows, and according to the list of technical specifications, in particular the supported sampling parameters and signal formats, it keeps up with the most advanced competitors. It has quite high quality – balanced, detailed, dynamic – sound, so that it will not become a weak link in a system with headphones and / or active speakers of a comparable price level. When used with a PC, it is worth taking care of a decent software player and its optimal setting.