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Project Pre Box S2 DAC & Headphone Amp Review

Jhify

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can't say I hear a big difference in sound, but where I do (it could be just my perception, though) it is with the MQA content from Tidal.
anyway, I'm selling the Matrix Audio DAC, and the PBS2D is just here to ease the transition to the coming Topping D90 (with MQA).

I don't know if there's any benefit to MQA format as a digital format at least I'm not earing any and I'm not sure science has proved any either so far but I don't think this is your perception. What I can hear is that a large amount of masters from tidal are coming from different mixes and mastering than the ones use for standard "Red Book"s. I beleive this is the main pro of tidal masters and what poeple are hearing and what I can hear : the master is mixed and mastered to have the best reproduction possible, has been approved by the artist (at least they claim they have) because it is meant to be played with higher end gear. whereas stardard Red Book pcm can be processed in the mixing and mastering process to sound better on the radio, car stereo, bluetooth mono speakers, etc. which can crush the dynamic range as well due to the loudness war and result in the lower quality reproduction with hi-fi gear. For exemple the latest from london grammar, even though it is 16bit /44.1k sounds like horribly compressed mp3 to me probably because of a dreadfull mastering. This doesnt happen with MQA versions. You can even find online a list of Albums from tidal where the PCM album and the MQA album don't even use the same recording in the studio. Anyway no need for a MQA DAC to access it but at least the MQA feature of the D90 shows it has a more modern and efficient USB implementation wich is great to have :) Enjoy your music !
 

Jhify

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well.. Forget everything I said. I just came accross few MQA records which are just as poorly mixed and mastered as the red book version. Seems like there's no standards and we just need to be lucky I guess :(
 

Shtruckk

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Hello,

Please help me with an advice : which is the best option between DAC ProJect Pre Box S2 and Topping dx3 pro v.2. The dac will be used only in a stereo system, headphone amplifier is not important from me. Both dacs are at the same price.

Thank you in advance
 

Jhify

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Hello,

Please help me with an advice : which is the best option between DAC ProJect Pre Box S2 and Topping dx3 pro v.2. The dac will be used only in a stereo system, headphone amplifier is not important from me. Both dacs are at the same price.

Thank you in advance

Same price ?? the Pre Box s2 is twice more expensive in my country.

If you're not an hardcode critical listener you'll be pleased with both just as much.

I'd go for the topping cause you can't switch off the Pre Box S2 it's really meant for desktop use and to be paired with a computer or a laptop. The PBS2 will always be on if not unplugged which can damage the oled screen over a (very) long time).

On another hand depending on where you buy the topping you might not have a good customer service or warranty.

Up to you depending what you need.
 

AudioSceptic

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If you don't need the HP amp, why not go for the Topping E30 or D10s?

I bought the Pro-Ject because I wanted the HP output and also prefer to buy European.
 

Shtruckk

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Thank you for the answer, both dacs are used, topping with almost 2 years warranty remaining and Pro-ject without. Both are at the same price. DX3 Pro have bluetooth 5.0, but if there was a noticeable difference regarding the sound in favor of the PBS2 i would have chosen him.
 

Jhify

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Thank you for the answer, both dacs are used, topping with almost 2 years warranty remaining and Pro-ject without. Both are at the same price. DX3 Pro have bluetooth 5.0, but if there was a noticeable difference regarding the sound in favor of the PBS2 i would have chosen him.

If there's a difference between two sonically (and there's most likely a tiny one) there's no better than the other it's a matter of taste and it's probably indistinguishable if you're just casually listening and enjoying your music sipping a tea so I'd just take the one the features that suit my needs the most.
If you have a doubt and want to get the one that sounds the best to you I'd get both and then sell the one you like the least.
 

AudioSceptic

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Thank you for the answer, both dacs are used, topping with almost 2 years warranty remaining and Pro-ject without. Both are at the same price. DX3 Pro have bluetooth 5.0, but if there was a noticeable difference regarding the sound in favor of the PBS2 i would have chosen him.
Is the used DX3 Pro less expensive than a new D10s or E30?
 

Shtruckk

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DX3 PRO it's at the same price like a new E30 + usb stick Cambridge Audio BT100 (i have a cambridge cxa 60).
 

VintageFlanker

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DX3 PRO it's at the same price like a new E30 + usb stick Cambridge Audio BT100 (i have a cambridge cxa 60).
Except the CA BT100 is Aptx-only compatible. The DX3 Pro supports Aptx-HD and LDAC. Plus, it will bypass your CXA-60 DAC we don't know much about.
DX3 Pro have bluetooth 5.0, but if there was a noticeable difference regarding the sound in favor of the PBS2 i would have chosen him.
BT 5.0 doesn't matter for sound quality (yet). It would however bring maybe more signal stability.

Both DACs are good. The DX3Pro clearly has a better IMD Distortion. I'm 90% no one would be able to distinguish both in DBT.

I suggest you go by features you need.
 
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AudioSceptic

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Expect the CA BT100 is Aptx-only compatible. The DX3 Pro supports Aptx-HD and LDAC. Plus, it will bypass your CXA-60 DAC we don't know much about.

BT 5.0 doesn't matter for sound quality (yet). It would however bring maybe more signal stability.

Both DACs are good. The DX3Pro clearly has a better IMD Distortion. I'm 90% no one would be able to distinguish both in DBT.

I suggest you go by features you need.
Can't say fairer than that. Go on features, or place of manufacture if that matters.
 

conuss

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Based on images from the Internet, I couldn't find the "Hi-Res audio" logo sticker on the case ... I can see it on the packaging, but it should also be on the case. Why isn't it?
 

Anatman

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This is a review and detailed measurements of the Project Pre Box S2 Digital USB DAC and Headphone Amplifier. It is on kind loan from a member. The S2 costs US $399 including Prime shipping from Amazon. I reviewed an early unit before I have my new audio analyzer so request was made to measure it again so here it is.

The S2 is a compact box with a color but grainy LCD:


Dedicated filter and Menu buttons make navigation easy.

The back panel has the usual connectors:

Since I tested the S2 using its USB port, I did not have to supply external power to it. Lack of external supply likely limits its headphone output level.

The S2 supports MQA which is still rare in lower end audio DACs.

The S2 uses ESS Sabre DAC which has a distortion compensation feature. The S2 is the only DAC I know that lets you turn that feature on and off. You will see its effect in measurement section.

DAC Audio Measurements
Let's start with our usual dashboard:
View attachment 40320

Even though distortion compensation is ON, we still have rather high second harmonic which brings SINAD which is sum of distortion and noise relative to main signal down fair bit. The ranking straddles two of our buckets:
View attachment 40321

This is not a good first impression for a product in this price range. I thought the news would be bad from here on, but that was not the case. The S2 produces a very quiet background: (should say 20 bits, not 20 dB)
View attachment 40322

This is just a few dBs shy of state of the art.

Good news continued into linearity measurement:
View attachment 40323

And jitter & noise measurements:
View attachment 40324

The low noise floor gave the S2 a leg up in the IMD versus level in the noise-dominated portion of that graph (sloping down):
View attachment 40325

As levels increase though, distortion takes over.

ESS DAC implementations tend to have a mid-level bump up in the above measurements. Manufacturers have lately been able to conquer that. Interesting that the S2 despite being an older design, is completely clear of that issue. So the secret was known earlier among some designers.

Multitone results are more hopeful than SINAD:
View attachment 40326

THD+N versus frequency swings back to disappointing side of the fence:
View attachment 40327

Filter response is standard affair:
View attachment 40331

Distortion Compensation
Turning off distortion compensation reduces performance substantially:
View attachment 40330

Can't imagine why you would want to turn this feature off.

Headphone Amplifier Measurements
Let's start with our noise measurement at just 50 milivolts to see if the quiet DAC noise floor shows up here:
View attachment 40328

Looks like the eye was taken off the ball here:
View attachment 40329

Sensitive IEMs will likely have some amount of background hiss at elevated volumes.

Power into high impedance load of 300 ohm is quite low:
View attachment 40332

Yet again we see elevated noise levels. The headphone amp is definitely noisier than the DAC portion.

Ditto for 33 ohm load:
View attachment 40333

This is very low power level. Hard to imagine a desktop product shipping with such low output level.

I thought maybe output impedance is high but it is not (thankfully):
View attachment 40335

Listening Tests
Not feeling good so I skipped listening to the S2. The numbers speak to inability to reach any decent level of loudness without distortion.

Conclusions
There are some really bright areas in performance of Pre Box S2. Its DAC has excellent noise floor, great accuracy in the form of linearity, and very low jitter. Distortion is high though for the class. That may not be an audible thing but the very low output levels of the headphone amplifier certainly is.

There are many good choices in this price range and lower so I can't recommend the Project Pre Box S2. But if you find a used one, pair it with a good headphone amplifier and you would be good to go.

--------
As always, questions, comments, corrections, etc. are welcome.

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Hi – and thank you for the review! The first time I read your review, I realized i had to add amplifiers to my rigs. So:
I now have two different rigs with based on each almost identical Lenovo ThinkPad L390 set up. I am mainly listening using Tidal via Audirvana.

Both rigs have each Pre Box S2 Digital, and one of them has the older Pro-Ject Head Box S (2011), and the other a new Pro-Ject Head Box S2. See pictures.

I have read a lot of confusingly – and thoroughly explained WHY - things about where the volume should be controlled from, find no agreement ore consensus. To put it short:

Do you think I should max out the amplifier, and control all the volume from the dac? Or should I max out the dac, and control all the volume from the amplifier? Or – a combination of both at different levels?

forum vennlig.jpgOppsett dac1.jpg
 

luisma

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Do you think I should max out the amplifier, and control all the volume from the dac?
In my case I set the DAC to zero (0) and use my preamp to do the volume control, if your amps allow it I would adjust the volume there.. The volume control on the DAC is a "digital" attenuator, it doesn't provide any actual "gain"
 

Anatman

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In my case I set the DAC to zero (0) and use my preamp to do the volume control, if your amps allow it I would adjust the volume there.. The volume control on the DAC is a "digital" attenuator, it doesn't provide any actual "gain"

Thank you! And yes, I have tried that solution also as it for me appear as the “logical” solution. But I have read a lot of different – for me as a layman in this completely over my head - views on this topic. One of many example:

“IMHO, the best recommendation is to adjust your amplifier for maximum volume, then just use the volume control on the DAC. That ensures only one volume pot is affecting the signal path (there are distortion and noise penalties with volume pots). The DAC volume is going to provide all the needed attenuation, assuming your amp is not an O2.There are examples of very high-end setups that work this way. ECP Audio, for instance, sometimes supplies high-end headphone amplifiers without a volume control and the volume is adjusted in their accompanying - but totally separate - DAC.”

Maybe one must be specific in detail of all the specs both to the DAC and the amp? And that there is many ways to go?
 

luisma

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It depends on the amps / preamps used, analog amp pots yes could introduce distortion, it all depends on which circuit and type they are based but good preamps and amps have excellent pots. As a matter of fact I use 3 volume controls.
Dac is always at 0db, then I use the preamp and also HQPlayer's DSP volume, the preamp is usually at 50 percent and HQPlayer is used to regulate from -25 to -3 that is the way I use it, since I'm upsampling (a better term would be resampling) the DSP in HQP provides no distortion. My point is the software DSP attenuation is more "reliable" in terms of digital reconstruction than the one in the DAC.
 

Anatman

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It depends on the amps / preamps used, analog amp pots yes could introduce distortion, it all depends on which circuit and type they are based but good preamps and amps have excellent pots. As a matter of fact I use 3 volume controls.
Dac is always at 0db, then I use the preamp and also HQPlayer's DSP volume, the preamp is usually at 50 percent and HQPlayer is used to regulate from -25 to -3 that is the way I use it, since I'm upsampling (a better term would be resampling) the DSP in HQP provides no distortion. My point is the software DSP attenuation is more "reliable" in terms of digital reconstruction than the one in the DAC.

Thank you! That seems logical to me. I have read around on this "topic", and can see there are huge variables due to differences in brands, lines, rigs etc. Fascinating.
 

vhild§

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If the headphone out is not good near max volume, does this apply also to the rca-out? Are these outputs married in some way?
 
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