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Review and Measurements of Pro-Ject Pre Box S2 Digital

Bjorn

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Amir has not tested the Lynx, but several others in the multi-thousand USD range. How high-end? And are you volunteering to pick them up and loan them to Amir for testing? :)

Actually anyone who owns a high-end DAC and would be willing to loan to Amir should get a donut or something...
I could as long as I don't have to pay for the shipping. I live in Norway. High-end it's not so much about price but rather related to quality. I consider both my DACs high-end, though the price range isn't in the "multi-thousand" range.


Thanks. At the last audio show I asked for review samples from a few companies and none were interested in having them measured. I felt like an insurance salesman. :)

I think a better model is for me to purchase equipment or members loaning them. That way there is no feeling of any obligation to manufacturer. We have had a few donations already but if we have any hope of reviewing expensive stuff, more is needed. :)
That's not surprising of we're talking about the typical high-end audiophile brands. Most of those have everything to loose on objective reviews and rather want to stay in the shadows combined with bs marketing.

However, there are serious brands out there and more so in the pro arena. I would encourage to try to contact Lynx.
 

sonci

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I remember reading that DSD implementation in Pro Ject is very good. According to the designer John W, latest Sabre chips are very good in this regard..
 

sonci

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I tested this with and without its wal-wart plugged in and it made no difference. Testing with LPSU requires a mini-USB jack. I made one but seemingly it has gone shopping or something because I can't find it. :D
I didn't see this reply, so basically you haven't used a linear Psu?
I really think it can better on clean power. If you got around any battery pack like Anker or so, you can use that, with any usb cable.
 

Randem Tox

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If you got around any battery pack like Anker or so, you can use that, with any usb cable.

This suggestion comes up a lot on CA and HF ... and seems to be based on the misguided notion that these USB "batteries" are somehow inherenetly low-noise in nature. In reality, most USB battery packs aren't much, if any, better than the included external PSU when it comes to electrical noise and some are a lot worse.

If they were simple batteries they might be, but the vast majority of them, including the Anker units, use switching step-up circuits (boost-converters) to get from the native 3.7v of the lithium cells they contain to the 5v necessary for USB power. If you're lucky, they include a decent regulator after the switch-mode boost converter but usually it's nothing special, certainly isn't chosen for audiophile noise concerns and not close to the performance of the better LDO regulators available.

There's a trade-off between regulator noise, current capability, thermal output and price and in a ~$20 retail power pack there's just no room on the bill of materials for a real low-noise, high-current, LDO regulator.

At one point I measured the included PSU, an iFi iPower 5V, a Mophie USB power-pack, an Anker USB power-pack, a couple of "who the hell are they" no-name USB power-packs and the USB-power being delivered by one of my laptops and one of my desktop machines. As I recall, they wound up in the following order from noisiest to quietest:
  • No-Name UPP 2
  • No-Name UPP 1
  • Desktop USB (from the main board)
  • Laptop USB
  • Anker UPP/included SMPS (tied)
  • Mophie UPP (barely better than the Anker)
  • iFi iPower 5v
I still have the actual measurements, as well as the specific battery pack models, but can't get at them until I get back from the trip I'm on.
 

stunta

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Actually I think Topping is more expensive, considering DX7 is not available.

The DX7s does not include a remote either (I managed to get a $20 universal remote to work with it though) which the Pro-ject does, but you get XLR outs and balanced headphone outs with the Topping which you don't get with the Pro-ject. If you don't need/want balanced outputs, I think the Pro-ject is the better deal here.
BTW I contacted RME to see if I can get accomodation pricing for their DAC. No reply so far. :( Can just imagine how welcoming they would be if I tried to get one for free to test! :)

Have you tried asking for a loaner unit that you would ship back after testing?
 
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amirm

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Have you tried asking for a loaner unit that you would ship back after testing?
No as I am keen on having one for future testing. That said, when I asked to buy Topping DX7s, they offered to send one to me without charge. So maybe they do the same. :)

BTW, they just contacted me back asking me where I am so that they can refer me to local people. Let's see what comes out of it.
 
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amirm

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Some measurement of this Dac on the Roon forum, shows that the coaxial input has a lot more jitter than usb. Have you tested it?
Of course. That is in the original review! :)

index.php


It shows USB being slightly worse but as I mentioned in the review, I re-tested later but could not duplicate. Both S/PDIF and USB produced the same excellent results.

Do you by chance have a link on where they posted measurements otherwise?
 
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amirm

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Hi @amirm

Long time lurker and fan of this site - just joined today after reading your review for this DAC.

Over on the CA Forum Jussi (HQ Player Founder) has posted measurements to show that DSD512 up-sampling performs best, closely followed by PCM768/32 up-sampling - and these perform much better in terms of jitter and distortion than 24/44.

Also he says compensation distortion definitely performs best, especially with linear phase + fast rolloff manually selected on the DAC. The "best" mode measures the worst for him and best mode automatically disables distortion compensation.

Are you able to perform measurements to compare DSD128 vs DSD256 vs DSD512 up-sampling with Roon, to verify these differences? And the same with PCM384kHz vs PCM768kHz up-sampling in Roon?

https://www.computeraudiophile.com/...easonable-cost/?do=findComment&comment=782311
Hi there. Welcome to the forum. Unfortunately DSD testing is not possible at this point because there are no DSD test files. I have tried to convert some of mine but I don't trust the conversion as analyzing the DSD files themselves is problematic!

I did take a look at his measurements there. I am assuming he measured them by using his software to format convert/upsample on the fly. I don't see any problems with 44.1 kHz data:

PreBoxS2-44k-Jtest24.png.53b5229a86a9ef66a3f85ac701df6843.png


This is done with a very large FFT causing the measured noise floor to go way down to -160 dBFS. And then those little spikes show up at whopping --148 dB or so.

This is his DSD measurement:

PreBoxS2-DSD512-Jtest24.png.51e4d1d76a6552fed79f62070a83d7dc.png


Couple of side bands vanish but again, they were all around -150 dB. All of these are completely masked by the main tone and at any rate, are well, well below threshold of hearing. "Splitting hairs" does not do it justice!

His distortion measurements show a better case but even there, there are issues. Here is his 44.1 Khz data:

PreBoxS2-44k-THD-graph.png.8133df38df4d4d8d352efa2ebf7548da.png



Why on earth is he going to 50 Khz when using 44.1 kHz sampling? We are not going to hear those ultrasonics anyway. The few spikes below 20 kHz are all below -120 dB so while the DSD one is somewhat cleaner, it is not something of importance here.

I do plan on testing HQPlayer at some point but for now, I would say even using his measurements, there is no difference to speak of between 44.1 and PCM 768 or DSD 512.

I will do more testing on distortion mitigation and report back.
 
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sonci

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The DX7s at 400 would be fantastic value, but at 500 is a bit steep, but you can't fault them if they Dacs measure this good.
I have a Topping TP20 in my bedroom that is going strong for about 5 years, mostly left plug in.
 
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amirm

amirm

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The DX7s at 400 would be fantastic value, but at 500 is a bit steep, but you can't fault them if they Dacs measure this good.
Just want to be clear that the measurements in this thread are for Topping DX7, not the DX7s. I agree with you that the price bump is not good for the DX7s. Fortunately the sale prices are reasonable at $370.
 

Sal1950

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The DX7s at 400 would be fantastic value, but at 500 is a bit steep,
I agree with you that the price bump is not good for the DX7s. Fortunately the sale prices are reasonable at $370.
Considering the audiophool community wouldn't think a DAC under 5 figures worthy of their time, I have to find these comments amusing. :D
 

Soniclife

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Can you confirm if the output voltage is the same in the various modes (best, test etc), if they are it will make it much easier for users to try to DBT these modes for themselves.
 

Rene

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Remember Sal: we are cheap around here! :D Need to save money for that good steak every night....

Bob.GIF


Do you have what it takes to become a QUANTUM MECHANIC?

Not just anyone can be a quantum mechanic. It takes determination, drive, imagination and money. Most of all, money. Bob is putting a son through medical school.

Nation crying for fully trained QUANTUM MECHANICS.

That's right, friend, the nation is crying for fully trained quantum mechanics. Can't you hear it? You can't? Well, be very still. Listen off in the distance. "Wahhh!" Hear that? That's the nation crying for fully trained quantum mechanics.

QUANTUM MECHANICS eat steak.

Yep, quantum mechanics make big bucks. Heavy bread. They're rolling in dough. They carry big wads of 10's and 20's in their pockets. A lot of MONEY. They drive Cadillacs and buy their wives minks. And they eat steak.
 

sonci

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Considering the audiophool community wouldn't think a DAC under 5 figures worthy of their time, I have to find these comments amusing. :D
With all due respect to Topping, but they can't price themselves at the same level as well established audio manufactures, even if their products are the same or better.
 

Music1969

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Hi there. Welcome to the forum. Unfortunately DSD testing is not possible at this point because there are no DSD test files. I have tried to convert some of mine but I don't trust the conversion as analyzing the DSD files themselves is problematic!

I did take a look at his measurements there. I am assuming he measured them by using his software to format convert/upsample on the fly. I don't see any problems with 44.1 kHz data:

PreBoxS2-44k-Jtest24.png.53b5229a86a9ef66a3f85ac701df6843.png


This is done with a very large FFT causing the measured noise floor to go way down to -160 dBFS. And then those little spikes show up at whopping --148 dB or so.

This is his DSD measurement:

PreBoxS2-DSD512-Jtest24.png.51e4d1d76a6552fed79f62070a83d7dc.png


Couple of side bands vanish but again, they were all around -150 dB. All of these are completely masked by the main tone and at any rate, are well, well below threshold of hearing. "Splitting hairs" does not do it justice!

His distortion measurements show a better case but even there, there are issues. Here is his 44.1 Khz data:

PreBoxS2-44k-THD-graph.png.8133df38df4d4d8d352efa2ebf7548da.png



Why on earth is he going to 50 Khz when using 44.1 kHz sampling? We are not going to hear those ultrasonics anyway. The few spikes below 20 kHz are all below -120 dB so while the DSD one is somewhat cleaner, it is not something of importance here.

I do plan on testing HQPlayer at some point but for now, I would say even using his measurements, there is no difference to speak of between 44.1 and PCM 768 or DSD 512.

I will do more testing on distortion mitigation and report back.

Thanks Amir! Yes the big picture from looking at Jussi's results is overall good performance, just like your conclusion - the differences he's shown are at very low levels, as you say.

Looking forward to your later thoughts on the distortion compensation feature. Jussi has mentioned (on that CA Forum thread) this is a feature of the ESS chip itself, not the DAC or XMOS interface of the DAC and that it only helps, it doesn't hurt in any of his measurements.
 

Music1969

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This suggestion comes up a lot on CA and HF ... and seems to be based on the misguided notion that these USB "batteries" are somehow inherenetly low-noise in nature. In reality, most USB battery packs aren't much, if any, better than the included external PSU when it comes to electrical noise and some are a lot worse.

If they were simple batteries they might be, but the vast majority of them, including the Anker units, use switching step-up circuits (boost-converters) to get from the native 3.7v of the lithium cells they contain to the 5v necessary for USB power. If you're lucky, they include a decent regulator after the switch-mode boost converter but usually it's nothing special, certainly isn't chosen for audiophile noise concerns and not close to the performance of the better LDO regulators available.

There's a trade-off between regulator noise, current capability, thermal output and price and in a ~$20 retail power pack there's just no room on the bill of materials for a real low-noise, high-current, LDO regulator.

At one point I measured the included PSU, an iFi iPower 5V, a Mophie USB power-pack, an Anker USB power-pack, a couple of "who the hell are they" no-name USB power-packs and the USB-power being delivered by one of my laptops and one of my desktop machines. As I recall, they wound up in the following order from noisiest to quietest:
  • No-Name UPP 2
  • No-Name UPP 1
  • Desktop USB (from the main board)
  • Laptop USB
  • Anker UPP/included SMPS (tied)
  • Mophie UPP (barely better than the Anker)
  • iFi iPower 5v
I still have the actual measurements, as well as the specific battery pack models, but can't get at them until I get back from the trip I'm on.

Hi. I don't believe noise output is the advantage that's discussed with these powerbanks - at least it shouldn't be, for the reason you mention, i.e. the noise output can be no different to a wall wart.

But one potential significant advantage could be eliminating a path for ground loops or mains leakage. One would then hope the noise output is then regulated by whatever it's powering, by low noise linear regulators.

But this is entirely system dependant of course. Some systems don't suffer audibly from ground / leakage loop issues, some may.
 
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