Pro-Ject Pre Box S2 Digital

Hi, does anyone know the difference between the Pre Box S2 Digital and the Head Box S2 Digital? As far as I understand it, the Headphone output chip is different (ESS9602 (pre box) vs. ESS9063 (head box)). Which one is better? I’m just interested in the Headphone output. What are other differences (besides the filters)?


MQA support.

When reading the spec I would say the Pre Box S2 Digital is a dual mono DAC design. The Head Box S2 Digital is not. So probably not the same design at all.

Hello, can someone confirm if it’s a bug or I do have a hardware problem?

Does your Distortion Compensate setting remains ON if you power off and then power on the unit?

With my S2, all the settings are retained (input, filter, volumes), expect for Distortion Compensate, which always comes back to OFF.

I think mine is the same, but I leave it on all the time so it don’t affect me. And to be honest, I don’t hear much difference with it on or off anyway.

Finally got her setup and firmware updated.

No Roon up-sampling yet - for the next couple of weeks I just want to hear the DAC’s own filters and for now I’ve gone for linear phase + fast rolloff - the most Chord like (on paper/description at least) which I’m used to now with my Hugo2. Distortion compensation enabled. Later, I definitely will go bonkers with Roon up-sampling.

Sadly my Sennheiser HD800S cans had to go in for warranty repair a couple weeks ago but my ears have been getting used to my Sony MDR1R Mk2’s these past couple of weeks. Hoping to get my Senny’s back asap.

Time to put her through the wringer :grin:

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This little thing is such great value and fun to listen to, even using it’s own filters.

I never doubted it’s DAC performance but I was sceptical of it’s headphone amp performance. No scepticism at all after listening to it.

Add me to the long list of impressed owners. Currently cranking this track very loud.

It might be my temporary spare Sony headphones but I don’t hear the huge/significant difference that others report with USB power vs 5Vdc external power. And that’s just with the DAC plugged directly into my 7-port SMPS USB 3.0 hub, not my Sonore Rendu. Maybe it’s different / more obvious using the RCA outputs at 2Vrms output. Just my initial observation. A big thumbs up so far.

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I’ve not been able to hear improvement of sound when using the stock ps or a degradation without. I’m using it as a preamp feeding Magni 2 and have used:

  • HD 650
  • Hiifman He-500
  • Audeze LC2
  • Grado gs1000e
    and just can’t tell…! So now I use only USB power (it’s directly plugged to my MacBook Pro by the stock USB cable that came with my HINT)… and still love it (particularly with the Senns… Hope you’ll like it more with your 800s.

Cheers Julio!

My expectation (bias) after reading numerous observations was that external power gives performance a significant lift but I haven’t heard it on first listening - maybe over time it will become more apparent. Here it was observed to give a 90% lift! :smile:

Of course that doesn’t mean there isn’t a difference - perhaps you and I both don’t have good hearing :joy: all said in good fun of course.

And more importantly, none of the above is terribly serious stuff. The fact that it sounds great with just a USB cable feeding it and better with a better PSU, is a win win for everyone.

The bigger news story for me is how the laws of diminishing returns are on full display (to me, my ears, my system).

And no dad, if you’re reading this, you’re not getting my Hugo2 :joy: but man does this little S2 DAC punch way above it’s weight. And I haven’t even gotten my hands dirty with any Roon up-sampling yet :grin:

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Spot on :ok_hand::grin:. Cheers

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Hello guys. At least 2 other users from another forum confirmed the same problem.

But I have some good news!

1- Pro-ject support kindly helped me to fix that. I have contacted them through the support site using Bermuda as my country (thank you Left Channel for the tip!) They answered my message 15 hours later with the solution. Much better than my expectations.

2- It’s not a firmware bug nor a hardware problem. I was another victim of the misleading user manual. The thing is that we need to push the volume knob to confirm the selection of the Distortion Compensate setting. I was changing the setting and pressing Menu again.

I replied them saying that an update to the user manual would be nice, as I was not the only one that faced that problem. I indeed remember someone posting about the misleading user interaction with the configuration menus some time ago.

The sound I get from this DAC is amazing, specially by upsampling to DSD512 with HQPlayer. Upsampling with Roon also gives great improvement and is not so CPU intensive as HQPlayer. Well, even pure Redbook from Tidal sounds great! This DAC has a great price/performance ratio!


Using external power in itself does not matter I think, its the quality of the power that matters. I notice a quite big difference using a cheap linear power, or a iFi iPower, compared to USB power from my computer. And the manual is wrong, its perfectly fine to use both USB power and the extra power through the micro USB connector. The DAC auto-switches to the micro-USB power when present (and shows a small symbol for it in the display).

But how much difference also depends on the quality of the USB power, maybe my computer gives crappy USB power.

Noted but I was comparing an Uptone LPS-1 (ultra low noise linear) vs SMPS powered USB hub… Maybe it’s just my bad hearing :smile:.

I personally think (I’m no expert though) it may matter even more if you’re using this as a DAC or Pre, i.e. you have it connected to another box (I’m thinking increased potential for leakage current loops etc). Using it with headphones, this is obviously not an issue. If you have this connected to another box (which has another PSU), then maybe leakage current loops come into it and maybe that’s where linear PSU’s have benefits (if I follow John Swenson’s teachings properly).

Who knows. As I mentioned earlier, it’s a minor thing anyway. John W should be very proud.

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I have mine connected direct to active speakers, and use it as a preamp/DAC combo. I haven’t done any comparison using headphones.

But try using the Uptone LPS-1 for a day or so, and then remove it and see if you notice anything.

This is exactly what I’ve done. I’ll see if my more revealing Sennheiser 800S cans show a bigger difference (or not) when I get them back from warranty repair.

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I use an USB 3 port, haven’t done any comparison myself but read somewhere that it would be better.

How did you manage to go up to DSD 512?

Use ASIO drivers and set DSD to native. From my testing, ASIO drivers works better. The SQ seems to be the same, but better DSD support in the ASIO drivers. You don’t get the Pro-Ject icon though when using ASIO drivers.

Why is MQA only available over USB?

Hehe, I suddenly feel like a support guy :slight_smile:

MQA needs some sort of CPU (its a software library from MQA that manipulates the digital stream), and on this DAC the XMOS handles this, so MQA is only supported on USB.

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