Pro-Ject Pre Box S2 Digital

Anyone listened to Pro-Ject Pre Box S2 Digital and have some insight? They won the EISA 2017 award and looking at its feature you would think it costs 5-10 times more than it does. But features don’t equal sound quality.

For example, how does it’s sound quality compare to Chord Mojo or ifi black label?

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Nice. On paper it definitely looks like it’s worth a demo / audition.

Nice touch with the 5Vdc input too - plenty of options whether it’s a 5V power bank, iFi 5V iPower, Uptone LPS-1, or quality linear PSU.

A well thought out Dac. Just needs a listen

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I believe the designer, John Westlake has been a little put out that some cheaper components were substituted for the first production run compared to his signed-off design. Apparently an agreement was reached that the original design spec would be faithfully reproduced in subsequent manufacture. I do t know where that leaves the first units in terms of quality or how one might be distinguished from a subsequent unit if the components do turn out to be different/better.


I will go and have a listen as soon as it hits the stores. When I asked a dealer in my city, he said it would be released September/October. For me it would function mainly as headphone amp. It is discusses in the latest Hifi & Musik,

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especially its price point - €349

I have a Hugo TT but sometimes get the itch for 512 DSD or MQA and this might be a very economical way to scratch that itch.



Sure does look tasy.

Perhaps @RBM could merge these threads

Those Pro-Ject guys seems to have a nice lineup. The twice as expensive DS2 Digital also looks very interesting, and has more cosmetic options. It also have a sub-out which I am interested in, but I am not sure there is any built in crossover setting for it.

Btw, those colorful waves on display is not there in real life I think, at least not as far as I could see on some youtube video. But its very small and neat though, perfect for desktop use below or on the side of the computer monitor.

Now, if only someone would review them and compare them to similar prices DACs like Mojo and ifi Black Label.

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Found some info about it here:

And I am guessing the EISA guys aren’t complete HiFi noobs, so all in all it looks very promising.

Hi Paul, was this stuff discussed on a forum elsewhere? Or just stuff you know from contacts.

I’m just wondering if there was an update on this and I’m hoping order has been restored with regards to John’s signed-off design.

She’s a little thing!

There’s a thread on pinkfishmedia and the comment came from John Westlake himself on there.

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Brilliant, thanks

Here is the thread for anyone interested:

As expected, John says it benefits with better external power supply and the fact that there’s a 5Vdc input (separate to the possible USB power) means people can choose whatever.

Will be interesting because iFi Audio have a new MQA compatible iDSD Black Label coming soon too.

I’m hoping for an iFi iDAC3 (or iDAC 2 Black Label with MQA). I might choose that over the Pro-Ject, feeding a separate amp.

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New review with Mojo and iDAC2 comparison (I think), but I don’t speak whatever language it’s written in (Spanish?). Anyone here speaks Spanish and can give a short summary? :slight_smile:


It is Portuguese and translation is possible dependent on what browser you use. He seems to like it, big on functionality but suffers in terms of absolute SQ compared to competition five times it’s price.

Cheers, I use Chrome and translated it, but the English was so strange I gave up :slight_smile:

According to the designer it benefits a lot from better power, so if I buy one I will use it together with for example an iFi Power (if that’s possible) or UpTone ISO Regen.

I think that refers to how it is independently powered so an LPS-1 or linear supply?

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hi i received yday Pro-Ject Pre Box S2 Digital.
Am using odroidxu4 (running Armbian builds of Ubuntu) as endpoint for Roon.
Worked immediately with no issues.
I also have a benchmark dac2 hgc (which i am currently using as preamp for pro-ject s2).
Love - all resolutions worked out of the box. PCM all the way to 768khz and DSD via DOP all the way to DSD256.
Sounds very good. Haven’t done a lot of critical listening - but i hear nothing worse compared to Benchmark DAC2.
Then I added patch (just to see) to Armbian build process to enable on linux also DSD512 and i guess native modes for DSD64/128/256 incl. 512. Just added one patch that makes kernel know the DAC (copied one line that folks added for Oppo Sonica).
Roon was able to use that with no issues as well … so i can play with upsampling of all content to DSD512 or PCM768 etc …
Remote (one that comes with it) is cheapo plastic bit bigger then credit card but works great for volume control and switching filters or on the fly or sources etc.
sounds GREAT to me.
things i love compared to Benchmark:

  1. switching between various sampling rate sources is practically instant. i.e. from 44.1khz CD to 192khz hires source or dsd is instant. on benchmark there was 0.4sec delay or you missed bit from start of the song. if all upsampled obviously none of the dac’s have issue with changing sampling rates but it makes me happy. i still use LMS from time to time so that comes in handy
  2. over 24+ hours no issues, clicks, losing sync etc … i think digital piece/USB is well implemented and has no obvious bugs …in spite of changing, reseting, roon and squeezelite - not once i had to reboot due to sw bug. that is great!!!. e.g. SMSL M9 DAC i also have works fine sounds good but when you reboot the pc or endpoint it starts with hiss until music app (roon or squeezelite) actually starts sending sometjhing (or even silence) … no big deal but bit annoying. as i am planning to replace benchmark dac2 with it and going directly to poweramp can not do that with SMSL m9 but think i ll have no issues with Pro-Ject S2
  3. it remembers volume setting upon power off … which is good if going to power amp directly
  4. MQA support - seems to work very well. 48 all the way to 192khz abd blue light works (tested with Roon/Tidal).

downsides compared to benchmark:

  1. does not have balanced out’s that my amp has (Bryston) … can use RCAs but would be nice if it was balanced
  2. don’t care about headphones so did not compare at all
  3. it can not be powered off (if powered or connected via USB only and source is powered its always powered). not a big . deal … just would be nice if you could power it off
  4. has mute on remote just like benchmark … what benchmark also did is ‘Dim’ which takes volume 20 or 30db down so if you get a phone call can still hear the music but at much lower volume instantly … just cool
  5. i miss ability to power up amp via preamp/dac. it requires 12V output and i guess it did fit in benchmark and pro-ject bing 2-4 smaller box it kinda didn’t fit. if i switch to pro-ject and eliminate benchmark as a preamp ill have to turn on/off amplifier manually and cant do it via remote no more :frowning:
  6. i wish pro-ject would display sample rate and depth. behcmark does it with LEDs … and smsl has info screen. not that it matters cause it DOES work whatever you send to it (16/24/32 bit and any sample rate) …

but benchmark is 2000EUR and Pro-ject 350. makes you wonder if its worth it.

So all i have left to do is do bit more critical listening and use Pro-ject direct into power amp rather then via Benchmark as preamp. … if goes well will sell behcmark if not ill keep it cause its just brilliant in terms of usability in my setup. biggest gripe i have is sample rate switching which DAC3 has fixed but thats 1500 EUR more then Pro-ject :wink: to fix that.


Cheers for the review, as expected they seem to have a very good price/performance, even though I doubt they are quite in the same league as the Benchmark DAC.

Have you tried giving them better power? For example, the 5v version of iFi iPower has a micro connector, would connecting that to the power in on the Pro-Ject DAC take over the power from the USB? Or maybe use them in combination with a vbus isolator.

Or maybe we have someone from Pro-ject here that can answer…pinging John Westlake :slight_smile:

hi Magnus, no i have not tried different power source(s) yet. Did try 2 different modes (though one is explicitly suggested not to be used - but i don’t know how it really works):

  1. power by SMPS adapter that comes with S2 to MicroUSB and computer connected via USB cable …
  2. powered by USB only by the same computer (nothing connected to Micro-USB) …

1st config -you are supposed NOT to use but not sure where it draws power from in that case - but it worked just fine and i heard no differences between the two scenarios.

Possibly with better power supply it might sound better but sounds silly to spend 100EUR+ to power a device that costs 350EUR… and though i have Intona USB isolating device - based on everything i’ve read it wouldnt really make any difference as S2 has excellent USB isolation built-in so didn’t even bother (left Intnona in front of Benchmark when used as a DAC). But if anyone confirms that iFi power which is 60-70 EUR i think makes a noticable difference ill go for it !

In the meantime got squeezelite to upsample (client for LMS) to 700khz+ for all content … funny what little sbc can do (Roon does it on a server so endpoints really need no computing power) … not that i can hear any difference compared to standard squeezelite @ 384/352khz) but it was fun tweak to try that too.

Funny part with Roon when upsampling to DSD512 is that it uses tons of CPU power - i do have xeon server (ranging from 2.1GHz to 3.1GHz depending on the load/cores turbo) … and for 44.1khz content it does 2x speed processing but with some DSD64 or HD (96/192khz) content it goes only 1.5-2x with multicore options selected - otherwise its even too slow)… either that technology needs serious horsepower or algorithms could still be improved a lot … i see only 2-3 cores sweating and all others not used).

Update after connecting S2 directly to power-amp. There might be a problem for me to use it in that way unless you guys have some idea:
Issue: when sample rate changes between the tracks very often i hear a farily loud click/pop between the tracks. I rebooted, powered off … changed settings in the DAC (filters and ‘distortion settings’ on or off) but that did not make any difference. i even inserted Intona isolater between by USB source computer and S2 just to be sure it’s not due to some ‘ground’ connection issues.

My guess is that it could be fixed in the firmware of the S2 (whenever input sample rate changes drive output to 0 in few ms and that i think could do it) … it happens when going from 44.1 to 192 and any other mix … some combo’s almost every time some not so often. Of course if I upsample all the content from Roon to 352 or 384 kHZ it is a non issue but then MQA support is gone etc.

Any thoughts/ideas ?

Thank you !