Review: Pro-Ject Audio Pre Box S2 Digital – upstream success

Pro-Ject Pre Box S2 Digital

Disclaimer: Pro-Ject Audio sent this unit free of charge, in exchange for a review. The Pre Box S2 Digital goes for 349 Euro, does MQA and DSD and takes in USB, coax, and optical signals. You can find out all about it here: Pro-Ject Pre Box S2 Digital.


Months ago Linus got me into Roon. It’s a program that I both use and respect. But truth be told I use iTunes more, but only because I’m stuck backing up phones and pads through it, through it updating iOS, and because I’m kind of an Apple guy, sticking it out. But iTunes sucks. Pro-Ject Audio’s Pre Box S2 Digital really got me back into Roon, which accesses a few key Pre Box features of which iTunes can’t take advantage, and which can net stabler and better quality playback.

Not sound


• Dual mono construction
• High end ESS Sabre ESS9038 dual DAC
• Proprietary clock circuity design
• Organic polymer capacitors and thin film miniMELF resistors
• MQA hardware decoding
• DSD64, DSD128, DSD256 & DSD512 (DSD over PCM)
• Up to 24bit/192kHz for optical & coax inputs
• 7 selectable digital filter characteristics
• 1 proprietary optimum transient digital filter
• Headphone output on the front (6.3mm)
• Synchronization of all internal oscillators
• Jitter as low as 100 Femtoseconds!
• Gold plated four layer PCB
• Full alu/metal sandwich casing in silver or black

The Pre Box S2 Digital is chock full of features. If it’s not one of the following filters: Fast Roll Off, Slow Roll off, Minimum Phase Fast, Minimum Phase Slow, Linear Apodizing, Hybrid Filter, Brickwall Filter, Optimal Transient- it’s its RCA outputs, dual SPDIF and USB inputs. Each filter feature is stored after the S2 is powered down. It’s a tiny box with a gargantuan feature set.

And, it’s as solid a box as I’ve seen at its size. Four visible screws keep everything tight. The S2’s back panel is flex free, and the thick extruded walls that keep its butt and face apart are thicker than the walls in the 2600$ USD Lynx Technology Hilo. The S2 Digital sports one of the clearest screens I’ve seen on any desktop audio device, bar none. It’s bright, legible, and its interface elements are well laid out. Being small, certain hardware feature UI toggles cut off, and if you’re a slow reader, you may not be able to keep up with the S2’s fast screen fades out. The only other problem is reach. Getting to the Filter and Menu buttons without nudging, muting, or otherwise touching the attenuator, is tough- which is probably why Project-Audio included a full-featured remote control. It plays and pauses Roon, raises and lowers volume, selects from any of the filters, and accesses the S2 Digital’s menu system. It’s a godsend for the butter fingered, and the slow reader.

In general, this bad boy is well designed.

Before we get on, I’ve got to admit my own stupidity. Initially, the remote control confused me. Do Pro-Ject expect me to kick back across the room from a box I can barely see? Do they think I’m that lazy? Am I the only one to whom this remote landed? It was my wife that found me. Evidently I was deep in a deep and dry squat, scratching my chin over a stretched Susvara line. She didn’t want to touch me. Thwack! Jabbing the manual in my kidney, she chirped: “Punch bug!” It’s a short affair, clear but forgettable. I’d browsed it on Pro-Ject’s website. Not that there’s much need. Because the S2 Digital is so small, and because I’m such a butter finger, I’ve taken to doing everything except volume adjustment through it. It’s a good, and necessary inclusion.

Another cool thing about the S2 Digital is that you can in instantly mute any input by quickly depressing the attenuator. Great design.

Sound and more after the jump:

3.7/5 - (153 votes)

Back before he became the main photographer for bunches of audio magazines and stuff, Nathan was fiddling with pretty cool audio gear all day long at TouchMyApps. He loves Depeche Mode, trance, colonial hip-hop, and raisins. Sometimes, he gets to listening. Sometimes, he gets to shooting. Usually he's got a smile on his face. Always, he's got a whisky in his prehensile grip.


  • Reply February 19, 2018


    Great review! The multiple inputs, remote control, display, and ability to play MQA really have my attention. Wouldn’t be using the amplifier section though and wonder if I would be wasting money on it.

    Currently use a Schiit Modi Uber for my speaker system and will sometimes hook up my iFi Nano Black Label as well for MQA listening. I’m considering an upgrade to a dac with more inputs that also plays MQA. For the same price, I could buy the non-multibit Bifrost and possibly upgrade in the future.

    Curious which I would get better sound with.

    Pro-Ject Pre S2 with MQA or Schiit Bifrost?

  • Reply April 21, 2018

    Phil Simpson

    Hi, great review. I was interested in the image of the Pre Box S2 and Apple Super Drive and was wondering if it’s possible to use the Super Drive dirctly as CD transport and control it (play, pause, skip etc) from the Pre Box S2’s remote.

  • Reply June 5, 2018

    Paul Donovan

    Hi, I received mine today. The headphone connection is terrible. You have to get it in exactly the right spot or you will be hearing distortion. I do not have this problem with other devices. I think it is the way it is manufactured but I am going to send it back and get another one. Sounds very good when the connection is working.

  • Reply September 27, 2019

    Steven Sylvester

    I was so very impressed by your reviews on the following three Headphone amps. since reading them I have tried very hard to pick a winner from the 3 contenders??


    I am a novice when it comes to audio and prone to wasting money through lack of knowledge you guys and contributors would be really helping if you can PICK THE NUMBER 1 FOR ME??

    I have never owned a real Hifi,let alone a headamp and Headphones,I have 3TB of music at 24\96 and upwards with some DSD files e.t.c. this music is held on SEAGATE EXTERNAL DRIVES played through a LENOVO IDEAPAD which only has USB Normal size + 1 x C-USB +headphone socket. I have no way to audition any of the above so expert advice is crucial and will be very much appreciated.

    Regards Steve

    PS I hate all FORUMS!!

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