Pro-Ject Pre Box S2 Digital

About The Pro-Ject Pre Box S2 Digital 

The Pro-Ject Pre Box S2 Digital is a massive amount of technology packed into a very compact box. Technically Pro-Ject put into the Stereo Preamplifier category, but we believe more of you will buy it because of its amazing performance as a Hi-Res DAC, and headphone amp all packed in one small, beautifully constructed, box packed with cutting edge performance. And did we mention price? How can they do it all at this amazingly low price? Please read on and see why it won the prestigious 2017-2018 EISA Award for Best DAC/Headphone Amplifier.

Pro-Ject Audio Systems currently produce 33 different models of turntables and a full 7 different series of electronics. This sheer volume of products is overwhelming, meaning it is sometimes hard to spot the real jewels in the range. One such jewel is their latest Digital Box design, the Pro-Ject Pre Box S2 Digital. It's a digital micro preamplifier that can fully unfold MQA files. If you aren't familiar with MQA, it stands for Master Quality Audio, and has been gathering momentum over the past few years for its ability to deliver very high-resolution audio over streaming. Tidal, for example, is currently offering a growing library of MQA audio files.

Design & Build Quality

Like most of the Pro-Ject Box designs, the Pre Box S2 Digital is tiny! It is 103mm wide, 122mm deep, and only around 37mm tall. It is housed in a very nicely finished all aluminium box. Like most of Pro-Ject's Box Designs, you get a choice of silver or black. The front panel has a full-sized headphone jack on one end and a small, but great feeling volume knob on the other end. In the middle is a tiny colour display window flanked on either side by two buttons that let you select the input, get into the menu, and change the filters.

The rear panel has inputs for USB B, coaxial digital, optical digital and a USB micro power connection. On the other end is a pair of gold-plated RCA analogue outputs. All of the connections feel very solid. A small remote control is included in the box, which gives you control over most of the functions of the unit. In addition, you can access the play/pause/forward/back controls from the remote. When connected via USB, you can even control them while streaming music from your computer.

With its very small footprint, the Pre Box S2 Digital will probably find its way into many different listening situations. It can be at home on your desktop either as a headphone amp, or DAC for your computer speakers or both. At the other end of the spectrum, it can hide out anywhere in your audio rack as a full-scale MQA capable DAC.

Finally, since it can even be powered off the USB input, you can use it on the go with a laptop. Even though you would think of it as a home-based component, it is actually smaller than some of the portable DACs available.

A Closer Look

While it may be tiny, the Pre Box S2 Digital is packed with features! We popped the cover off to take a peek inside and found it to be totally stuffed with components. Upon closer examination, you'll see that it's a completely dual mono design, with each channel of the signal path mirrored. Pretty impressive for such a well-priced component!

ESS Sabre ESS9038 Dual DACs: Pro-Ject opted for the ESS Sabre ESS9038 dual DAC in the Pre Box S2 Digital — the highest level DAC they have ever used. These dual DACs are capable of up to 32-bit PCM 768kHz and DSD512. It's important to point out that MQA unfolding and the higher resolution digital rates are only available on the USB input. The optical and coax digital inputs do not do MQA, but still go up to a very respectable 24-bit/192kHz. Pro-Ject made the decision to limit these two to keep the price down. If they made it available on all inputs, we would expect it to cost around twice the price. Most people are going to be using the desktop or laptop version of Tidal to play back MQA files, and the USB connection is best suited for that application.

Ultra Low Jitter: Pro-Ject also spent a lot of time developing the clock used in the Pre Box S2 Digital. While digital audio can be great, jitter is one downside. If the digital signals are not put back together with the same timing as the original recording, the music seems to lack emotion, no matter how clear it may sound. The Pre Box S2 Digital has one of the lowest jitter rates we have ever seen, far surpassing some much more expensive units.

Components: While it would have been easy for Pro-Ject to skimp on components, especially considering how inexpensive this unit is, they instead opted for some very high-end parts.  It is quite unusual to see organic polymer capacitors and thin film miniMELF resistors in the power supply inside a box selling for this price! Pro-Ject even used a 4 layer gold plated circuit board with extra shielding.

Since Pro-Ject felt this unit would mainly be used in USB mode, they also spent a lot of R&D time coming up with a way to reduce all of the noise that is present on a typical computer USB connection. Many components use passive filtering, but Pro-Ject used a special combination of passive and active filtering which brought the noise levels to below -130db. This is a ridiculously low number! All of this translates into great sound with a super low noise floor. When listening to this unit, you never get any trace of background noise.

Filter Options: The Pre Box S2 Digital also has some filter options that allow you to shape the sound. These are subtle and recording dependent, but can make a bright or edgy recording sound better. There are 7 choices that you can easily flip through.

The output of the analogue jacks is right around 2 volts, so you can use this box as an audio DAC by just setting its output to 0, which is full gain on this unit. If you have a fairly sensitive power amplifier, it will even make a great digital preamp with its three inputs. The headphone amp is another ESS design and it can support up to 600-ohm headphones. Finally, for you Roon fanatics out there, the Pre Box S2 Digital is also Roon capable.

Remote Control: The included credit card-sized remote control is aptly named Control it - a surprisingly luxurious remote control which not only controls your hardware but also your software. With the help of this remote control you are able to send the commands Play/Pause and Next/Previous to your playback software. Additionally, Control it allows you to switch or "cycle" between digital filters. Of course you can also set your desired volume with this control.

Control it is made from 100% aluminium and delivers extremely nice and simple aesthetics. The high quality design perfectly suits the audiophile quality Pre Box S2 Digital.

About Pro-Ject

Pro-Ject Audio Systems was founded in 1991 by Heinz Lichtenegger. The products are designed in Mistelbach, Austria and exclusively made in Europe at manufacturing plants in the Czech Republic and Slovakia and then shipped to more than 80 countries world-wide. Pro-Ject are best known for their high quality belt drive turntables which are often seen as the best in class at their various price points. In particular the Debut series of turntables has been the go-to record player of choice for many a budding music lover at the affordable end of the price spectrum.

Pro-Ject turntables allow you to experience again the clarity, warmth and magic to be found in the grooves on your vinyl, at very reasonable prices. With simple designs and high construction standards, performance has always been the priority. Fully manual operation coupled with the best materials and components available at each price level ensures the best possible value. Of course, here at Audio Trends, we've been selling them since the beginning of time (almost) and due to our passion for all things analogue - read vinyl - can tell you everything you need to know about our fantastic range of their products.

Whilst turntables are a large part of the Pro-Ject story the company has also ventured into high quality micro sized audio products in recent years including phono preamps, DAC's, streamers and amplifiers.

Pro-Ject Pre Box S2 Digital Reviews

The Pre Box S2 Digital has critics and audio nerds raving about this multi-talented mini. For example:

"The S2 Digital is a flexible piece of kit, fulfilling a multitude of briefs for a sky-high value quotient. That in itself makes the Pro-Ject box a good choice. When the upgrade itch strikes, repurpose rather than sell-on." – Phil Wright, Hi-Fi Reviewer.

"I have two here now, they are too good to not have an extra. It's audio archaeology. You play familiar stuff and hear new things. Even tracks I recorded 35 years ago sound stunning with new information heard. I caught some low level talking on a mix that I never heard when I tracked it." – Jim Williams, Gearslutz Forum.

Even the tech heads are impressed! The folks who pore over every capacitor and chipset were impressed overall with the Pre Box S2 Digital's hardware and design.

"The Pro-Ject Pre S2 Digital is a well-built, and well-thought out DAC. Excellent attention is paid to isolation of digital and analog. Layout is very good for such a small unit. Mechanical construction is also quite solid and overbuilt compared to much lessor designs" – AudioScienceReview.com

"The Pre Box S2 Digital offers audiophiles a very high-value DAC/digital preamp at an almost ridiculously low price. Not only does it include a plethora of important features and capabilities; it also sounds good, has an elegantly designed control surface, and is expandable. As an audiophile's needs grow, Pro-Ject micro-systems have the components to support nearly every potential input source and format available through various accessory units designed to perform specific functions. While not quite bespoke audio, the Pro-Ject Pre Box S2 is one small part of an elegant system that gives even audiophiles with limited means a way to assemble a first-class system. One of TAS' 2018 DACs of the Year." The Absolute Sound Editors' Choice Awards 2023