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Pro-Ject Pre Box S2 Digital: MQA HW decoding at reasonable cost


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On 2/23/2018 at 7:22 PM, fgribas said:

 

@Miska apart from the confusion regarding user settings, could this be the reason for what I'm talking about? It seems that on firmware 2.12 the flag inverted, and using Disabled apparently turns on this ESS chip feature. Someone mentioned it on Amir's forum also.

 

What FW version you had when you measured Dist. Compensation On/Off ?

 

Probably I tested it with the shipped firmware (2.11?) because I did it pretty much straight when I got it. Measurement files are dated October 23/24 2017. I didn't write down the firmware version though.

 

I'll re-check again with the 2.12 firmware next time I measure something on this desk. (it takes two hours or something like that to set up things and do the measurements)

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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6 hours ago, Miska said:

 

Probably I tested it with the shipped firmware (2.11?) because I did it pretty much straight when I got it. Measurement files are dated October 23/24 2017. I didn't write down the firmware version though.

 

I'll re-check again with the 2.12 firmware next time I measure something on this desk. (it takes two hours or something like that to set up things and do the measurements)

 

Great, thanks! Opinions are conflicting across different forums regarding this.

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1 minute ago, fgribas said:

Thank you @Miska

 

So you get less distortion with the feature enabled, as it really should work. As per my understanding, it's the opposite result of Amir's tests.

 

Depends which one of his tests you check. Because they are self-contradictory. His tests show poor results with profile "Best" (dc disabled) and better results with profile "Test" (dc enabled). While elsewhere he notes otherwise.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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2 minutes ago, Miska said:

 

Depends which one of his tests you check. Because they are self-contradictory. His tests show poor results with profile "Best" (dc disabled) and better results with profile "Test" (dc enabled). While elsewhere he notes otherwise.

 

 

Yes, his second round of tests were when the confusion started. I think I'll stick with your results

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I don't give a ra about Amir's tests and charts I want to know how the damn thing sounds and is it good value? More posts need to concentrate on sound quality. Going back through many pages of posts @left channel said:

 

Quote

But I've decided I prefer my Modi 2U for a desktop DAC after months of listening, and also because it just works, is well-made, and well-supported. My first item for sale in the Superphonica marketplace may be this Pre Box S2 Digital — and my second may be a Pro-Ject Amp Box — but I will wait at least until the next firmware update comes out so I can offer it with that installed.

 

This is useful information and what this thread needs more of.  How does MQA streamed through Tidal sound? Is it remotely comparable to a Mytek Brooklyn DAC+? I don't think the Liberty is even shipping yet so there are no real reviews of that unit yet just promos AFAIK.

 

Torq over at SBAF is taking his time with the full review. I really appreciate all the time and effort @left channel put in.

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30 minutes ago, exdmd said:

I want to know how the damn thing sounds and is it good value?

 

It sounds good, and is certainly good value, can beat bunch of more expensive DACs.

 

30 minutes ago, exdmd said:

How does MQA streamed through Tidal sound?

 

I couldn't care less about MQA. But RedBook streamed from Tidal and upsampled to DSD512 for playback sounds good, as do my CD rips.

 

32 minutes ago, exdmd said:

Is it remotely comparable to a Mytek Brooklyn DAC+?

 

Brooklyn is in entirely different price category, so I don't see the point in comparing those.

 

35 minutes ago, exdmd said:

I don't think the Liberty is even shipping yet so there are no real reviews of that unit yet just promos AFAIK.

 

AFAIK, Liberty uses cheaper DAC chip and is limited to 384k PCM and DSD256, while costs 2x. Just as spec comparison.

 

Signalyst - Developer of HQPlayer

Pulse & Fidelity - Software Defined Amplifiers

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2 hours ago, fgribas said:

I have a 5v USB power-bank. When I connect the S2 to the 2.1A port of the power-bank, the sound is better than using the included wall-wart. When I use the 1A of the same power bank, the sound is even better. Must be something related to the low quality voltage regulators on the cheap power-bank.

 

I noticed the same. I measured and the external 5Vdc input of the S2 DAC only draws a maximum of 0.5Amp, so a 1Amp PSU or powerbank is all you need.

 

I thought that even though the DAC can work powered by USB 2.0 only, I thought maybe with external power it draws a little more power but it doesn't - it's still 0.5Amps max drawn.

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Really interested thread about this DAC, I'm looking further for someone testing it with a linear PSU as well.

I like the idea of dual ES9038 DAC; with a bit of tinkering and re-wiring this could be a decent balanced DAC as well (well, at least by looking at chip specs and ESS recommended design).

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25 minutes ago, trl said:

I'm looking further for someone testing it with a linear PSU as well.

 

For the sake of testing the improvement with a clean and decoupled PSU, would it be practical to power the DAC from 4 x NiMH cells, using something like this:

https://www.aliexpress.com/item/4-8V-6V-Battery-Box-With-Switch-4-AA-Batteries-Stack-USB-Battery-Storage-Clip-Holder/32820217325.html

 

I reckon I would get about one hour of battery life - plenty for a bit of experimentation.

 

I guess this has been tried before, and there's a good reason why others are not trying it? Perhaps the source impedance of raw NiMHs is too high?  Add a capacitor in parallel (to reduce source impedance)?  Or perhaps that then causes problems with in-rush currents? (My Pre Box S2 Digital is still on order)

 

(I assume that 5V phone power banks must use some switching and therefore inject loads of noise.)

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I would suggest more than 5V batteries, then a DC-DC step down low noise & low dropout regulator. You really need a very stable power supply for the DAC. Also, try not using the power banks with lithium batteries inside...they tend to have lot of ripple & noise from their SMPS DC-DC buck converters!

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Pro-Ject are coming with their own battery based PSU soon - a battery box known as Accu Box S2 USB

 

Might be worth waiting for this.... 

 

http://pinkfishmedia.net/forum/threads/pro-ject-pre-box-s2-digital-dac.201691/page-24

 

No word yet on it's battery life but if it's anything over 8 hours continuous playback at max current draw, with ultra low noise regulators, I'd be happy. Just let it re-charge overnight.

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36 minutes ago, trl said:

 You really need a very stable power supply for the DAC.

Thanks trl. If what you want is stability, then you cannot get a more stable supply than batteries plus a low-inductance capacitor. Now - that may not be good enough (low impedance at all frequencies? In-rush current control? Something else?) - but it will be stable.

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If you look at all the measurements done by @Miska you will notice very good performance and he is using SMPS that was delivered with the box (if I understood him correctly). So probably there is no need to spend too much time and money thinking about power supply as the small DAC with ES9311 chip is designed in a way that at least can give good performance with standard in box SMSP or in spec USB power. Would it measure bit better with LPSU? Maybe, but probably it won't be audible. 

Here you can read bit more about ES9311 - http://www.esstech.com/index.php/en/products/low-noise-low-dropout-regulator/

 

I have Tomanek ULPS 5V but do I hear the difference against standard SMPS? Not really :) 

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59 minutes ago, Mark Dirac said:

Thanks trl. If what you want is stability, then you cannot get a more stable supply than batteries plus a low-inductance capacitor. Now - that may not be good enough (low impedance at all frequencies? In-rush current control? Something else?) - but it will be stable.

Batteries are not stabilized over time, so now you might get 1.24V/element and after few hours you could be getting 1.19V/element. So, I still think a 7.2V battery followed by a low-drop & low-noise regulator could be better.

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9 hours ago, PunkRiot said:

So probably there is no need to spend too much time and money thinking about power supply as the small DAC with ES9311 chip is designed in a way that at least can give good performance with standard in box SMSP or in spec USB power.

 

I'm not sure the recommendation for a linear PSU (or batter) power is related to noise output - the S2 DAC has nice regulators inside as you say.

 

I think it may be more due to AC mains leakage (currents) associated with SMPS's. Linear PSU's have lower levels.


It all depends on what else connects to the DAC of course and how any ground / leakage 'loops' are formed. If only using the S2's headphone output, then none of this matters of course. But if using it as a DAC you may (or not) hear differences with a linear PSU.

 

Just a thought. The DAC sounds great with just the stock PSU. But you may (or not) be able to squeeze even better performance with the PSU side.

 

The designer himself (John Westlake) has recommended this on the pinkfishmedia forum...

 

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On 2/27/2018 at 5:23 PM, fgribas said:

There are a lot of SQ impressions on this thread. I will write down my opinion.

 

Well, this DAC really shines on DSD256 and DSD512. PCM 768/705 is also very good. 

 

MQA is nice, but the quality of the MQA Mastering is different on every MQA album available on Tidal. With some albums I prefer (by a small margin) the MQA decoded version than upsampling to DSD512. On other albums, upsampling to DSD (therefore not decoding MQA), sounds much better than decoding MQA. It's well known that MQA uses poor/low performance filters (even an Audioquest Dragonfly has processing power to use these filters). Sometimes the poor filter can sound nice (master engineers/record labels supposedly use the best available MQA filter to fit each album they encode to MQA), but sometimes it sounds simply not good.

 

For me, this DAC sounds amazing! Before mine arrived here, I ordered a Schiit combo: Magni 3 + Loki Mini. In a nutshell: I will sell them. I prefer the ESS headphone amp embedded on S2 than the Magni 3. The M3 colors the sound, loses details and changes the soundstage (in a bad way). The Loki equalizer is fun to play with, but can't rectify the M3 mutations on the sound.

 

Unless my RCA cables are really bad (Schiit cables by the way), I don't consider the M3 as a neutral amp, and consider a downgrade compared to the S2 internal headphone amp.

 

If someone has the initial impression of S2 as being something like "anemic", O.S. optimizations and good quality upsampling can bring a lot of weight and life to the sound. And every system is unique.

 

Every little detail changes the sound. My laptop has 2x USB and 1x USB-C ports. The sound changes drastically when I connect the S2 to each of these ports. USB-C is the best in my system. I think it is the most isolated (less shared) bus internally.

 

I have a 5v USB power-bank. When I connect the S2 to the 2.1A port of the power-bank, the sound is better than using the included wall-wart. When I use the 1A of the same power bank, the sound is even better. Must be something related to the low quality voltage regulators on the cheap power-bank.

 

When using my laptop on batteries, the sound is great, even with the noisy fan on the laptop running on to cool the 3.7GHz fixed overclock. When I plug the SMPS power supply (dell standard) on the laptop, the sound gets very worse.

 

Even by making simple optimizations on a standard Windows 10 like core isolation (processor affinity) for the player process, changing process priority (real time or high priority) of the player process and lowering the O.S. Timer Resolution can bring noticeable improvements on the sound.

 

Digital Audio is tricky and complex. You gotta deep dive and study... Or spend more money to get the same SQ.

 

I'm still waiting for a fanless mini-PC to arrive here, it will be a NAA/Roon-Endpoint. Also waiting for one Linear Power Supply for the DAC and another one to the mini-PC. They should improve even further my SQ.

 

The thing is: the DAC (or any other system component) can sound very different on different systems. And there's also personal preference... For me, it sounds great! Specially for its price and size. If you can buy it having the chance to return, you can give it a shot. I could not return it and I'm happy I liked it.

 

Torq over at SBAF considers the headphone amp built in to the Pre Box S2 to be not so good:

 

Quote

Pair it with something like a Magni 3 or a Vali 2 and that utterly annihilates the built-in headphone output

 

I happen to have both a Magni 3 and Vali 2 and would be glad to compare a review sample of the Pre Box S2 using both amps.  No interest in buying one though.

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