Pro-Ject Pre Box S2 Digital review

A tiny DAC and headphone amp that’s big on features Tested at £295

Pro-Ject Pre Box S2 Digital review

What Hi-Fi? Verdict

The Pre Box S2 Digital is superbly specified and sounds pretty good too


  • +

    Impressive feature list

  • +

    Compact and nicely made

  • +

    Balanced and clean delivery


  • -

    Exceptional competition

Why you can trust What Hi-Fi? Our expert team reviews products in dedicated test rooms, to help you make the best choice for your budget. Find out more about how we test.

When we think of Pro-Ject, the company’s excellent affordable turntables first spring to mind. But alongside these, and a number of premium record players, there has long been a line-up of ultra compact electronics.

We have found these electronics to be somewhat of a mixed bag over the years, but that hasn’t stopped the range from growing to a point where it now includes CD players, streamers, phono stages, amplification and now DACs such as this one.


Pro-Ject Pre Box S2 Digital features

Take a look at the Pre Box S2 Digital’s feature list and it’s fair to say Pro-Ject has ticked every meaningful box. The Pre Box will play PCM files up to 32-bit/768kHz and top out with DSD512, so file compatibility isn’t an issue. If you’ve got it, the chances are that the Pre Box will play it. Even MQA decoding is included, which is still something of a rarity regardless of price level.

Inside the S2, you’ll find the highly regarded ESS Sabre ES9038 dual DAC chip mated to a proprietary clock circuit and carefully chosen components to optimise performance. The main board is a gold plated, four-layered design with low jitter high on the priority list. You get the impression that Pro-Ject’s engineers have tried hard with this one, particularly considering the Pre Box’s price is as competitive as it is.

There’s the usual trio of digital inputs – USB (type B), optical (24bit/192kHz) and coax (also compatible with up to 24bit/192kHz files) alongside a single pair of variable analogue outs. Power is accepted through a 5V micro USB socket, though you won’t need this if you connect through the Type B USB input, as the S2 will just take power from that.


Pro-Ject Pre Box S2 Digital build

Around the front there’s a small, just about adequate display that shows volume level, input chosen and the sampling rate of the incoming signal, and next to it, a volume control.

Despite taking up about the same amount of space as a coaster this little box can not only work on a desk next to a computer but also as the digital hub in a hi-fi or two channel TV-based audio set-up. It’s so small it can fit just about anywhere and a credit card remote helps when the unit is used in this way. 

Build is robust enough and the stepped rotation on the volume control feels good. We’re a little less taken with the sharp-edged front panel control buttons, but on the whole Pro-Ject has done a solid job.


Pro-Ject Pre Box S2 Digital sound

Much the same can be said about the sound quality. Using our resident MacBook (loaded with a range of hi-res and CD grade files) things begin well. The Pro-Ject has a crisp, fairly detailed delivery that has more in the way of precision and grip than the headphone output from the computer itself. It’s a fast, agile sound, one that might lack a little in terms of natural warmth and richness but tries to make up for it with a pleasing clarity and evenly balanced presentation.

We play a range of music from Yellow Light by Of Monsters and Men and Beethoven’s Midnight Sonata to Nirvana’s Nevermind and the Pro-Ject treats each recording with equal care. Bar the slightly lean balance we have no real complaints about the S2’s tonality. It’s convincing enough and is helped by a good level of refinement that prevents the DAC from making a meal of harsh or aggressive recordings.

Pro-Ject Pre Box S2 Digital tech specs

Inputs USB, coax (RCA), optical

Outputs 6.3mm headphone, variable out (RCA)

Frequency response 20Hz-20kHz

Impedance 8ohm

Dimensions (hwd) 37 x 103 x 122mm

Weight 366g

There’s enough in the way of rhythmic drive and punch to allow Nirvana a pleasingly free reign while the DAC’s composure and organisation keeps enough of a grip on the various musical strands to keep things easy to follow and enjoyable.

The Beethoven piece shows the Pro-Ject is capable of subtlety and of delivering a harmonically rich instrument such as a piano with conviction and stability. Dynamics are rendered with care, though compare the Pre Box with established benchmarks such as Audioquest’s Dragonfly Red (£169) or Chord’s truly exceptional Mojo (£399) and it’s clear that it’s behind class leading levels when it comes to dynamic expression, detail resolution and rhythmic precision.

The story stays the same regardless of whether the Pro-Ject is used with our laptop and headphones or as the digital hub in a two-channel speaker-based set-up.

We try a range of headphones from the Beyerdynamic T1s and Grado’s RS1s to AKG’s K550s and the Pro-Ject is capable of a good level out of each of them. While it doesn’t have the outright transparency and resolution to make the most of the Beyerdynamics or Grados it doesn’t sound obviously overwhelmed in such company either.


The Pre Box S2 Digital is very well specified, nicely made and sounds pretty good too. Add its compact size into the equation and in some circumstances it could prove ideal.


  • Sound 4
  • Features 5
  • Build 4


Best DACs 2019

Read our Audioquest Dragonfly Red review

Read our Chord Mojo review

What Hi-Fi?

What Hi-Fi?, founded in 1976, is the world's leading independent guide to buying and owning hi-fi and home entertainment products. Our comprehensive tests help you buy the very best for your money, with our advice sections giving you step-by-step information on how to get even more from your music and movies. Everything is tested by our dedicated team of in-house reviewers in our custom-built test rooms in London, Reading and Bath. Our coveted five-star rating and Awards are recognised all over the world as the ultimate seal of approval, so you can buy with absolute confidence.

Read more about how we test