[Mark Dirac]

I've successfully connected the Pre Box S2 Digital to an Android phone and the UAPP app, via a UTG adapter cable. However, I needed to put my USB REGEN between them. My externally-powered Schiit Modi 2U connects fine with or without the USB REGEN, but the Pre Box needed the REGEN's help.

Power: My phone is a Pixel XL. When connected directly to the Pre Box I get the Android "USB Supplying Power to Attached Device" message, but the phone does not supply enough power and the Pre Box does not turn on. Powering the Pre Box with the supplied wall-wart didn't work either: the Pre Box powered on, but UAPP could not find it. But after disconnecting the wall-wart and inserting my USB REGEN, the Pre Box powered up and UAPP found it.

Play: I used UAPP to play several HDtracks hi-res files, and the Pre Box reported the sample rates perfectly. I then tried streaming from Tidal and Qobuz using UAPP, and found that unless I enabled bit-perfect in Settings anything above 44.1 kHz would stutter. I used UAPP to test Tidal HiFi, MQA, and Qobuz low + Hi-Res. Everything was detected and sounded as expected, with one minor exception that I suppose is due to the way MQA works: during MQA streaming, UAPP showed 48 kHz which is what it sees in the package it's sending, and the Pre Box displayed 192 kHz which is the result after unfolding in the DAC.

Success. Not a portable solution without a better power source, but interesting. I'm looking forward to seeing someone try this with an iPhone or iPad. I tried an Android tablet, a Pixel C, and couldn't even get the "USB Supplying Power to Attached Device" message, but I assume with the USB REGEN inline I would be able to do the same as above with my tablet.

And yes, I get the popping noise in this app too. Can't wait for the firmware update.

-----
Edit: clarified "my Schiit Modi" is "my externally-powered Schiit Modi 2U".

Well I finally got around to buying a USB C otg adapter for my new LG G6, and am thrilled to report that it plays to the S2D.

Playing Tidal, the S2D's display reports 96kHz, which puzzles me. I would expect it to show 44.1kHz or the Android's native sampling rate of 48kHz. (MQA is not available on the Tidal Android app. And I cannot believe that the app is sufficiently sophisticated to decide to upsample to 96kHz. So what is upsampling? Puzzling.)

The wall wart is needed to get the S2D to power up, but thereafter the wall wart can be disconnected, and the S2D is happy to be powered from the LG G6. Battery drain of the LG G6 is pretty high - I guess a 100%-full battery would be drained in about 4 hours. Battery drain is reduced a little by plugging back in the wall wart. (I can still hear no change in sound, on my LCD 3 headphones, with the wall wart connected or disconnected.)

It's a pity that we never found out what the wall wart is powering. Clearly, the S2D needs not only voltage but a fair bit of current over the signal USB from the host, particularly when starting up. But the wall wart seems to be powering only a proportion of that current through the power USB, and is not essential.

I am curious as to how it would sound if I found a USB C otg adapter with a power-injection socket. The S2D seems to be well-designed to smooth away noise from the wall wart on the power-input USB socket, but would it be able to smooth away noise from a switching wall-wart supplying power into the signal (host) USB?

I have updated the summary document slightly.

 

[Left Channel]

Playing Tidal, the S2D's display reports 96kHz, which puzzles me. I would expect it to show 44.1kHz or the Android's native sampling rate of 48kHz. (MQA is not available on the Tidal Android app. And I cannot believe that the app is sufficiently sophisticated to decide to upsample to 96kHz. So what is upsampling? Puzzling.)

Very interesting, thanks for testing! Re the section quoted above, I believe you are seeing 1x MQA unfolding by the Tidal app. If so, the S2D MQA indicator should glow pink/purplish instead of green or blue. Yes?

The Tidal app's MQA unfolding currently works with the internal MQA-capable DAC in my LG V30 phone, and also with external USB-connected DACs. You'll see no higher than 96 kHz because it will only to the 1x software decoding itself, and offers no way to send a bit perfect raw MQA stream to the external DAC for decoding.

The UAPP app for Android would take your LG G6 to to the next level, as it includes Tidal integration and the ability to send raw bit perfect streams over USB. (For any iOS users reading this, I'm unaware of any such third-party iOS apps with integrated Tidal streaming.)

 

[Mark Dirac]

Very interesting, thanks for testing! Re the section quoted above, I believe you are seeing 1x MQA unfolding by the Tidal app. If so, the S2D MQA indicator should glow pink/purplish instead of green or blue. Yes?

The Tidal app's MQA unfolding currently works with the internal MQA-capable DAC in my LG V30 phone, and also with external USB-connected DACs. You'll see no higher than 96 kHz because it will only to the 1x software decoding itself, and offers no way to send a bit perfect raw MQA stream to the external DAC for decoding.

The UAPP app for Android would take your LG G6 to to the next level, as it includes Tidal integration and the ability to send raw bit perfect streams over USB. (For any iOS users reading this, I'm unaware of any such third-party iOS apps with integrated Tidal streaming.)

Well Left, your news opens a whole new avenue / freeway of investigation. I am amazed that Tidal would include MQA in their Android app, but not get around to telling anyone about it. No, hang on, I'm not amazed, I am disappointed.

In the meanwhile and fyi, the technically astute Mr. radamel over at Pink Fish recommends an alternative Android app "mconnect" for streaming MQA from Tidal via Android:

Tidal Masters (MQA) using ChromeCast Audio | pink fish media

mconnect Player Lite – Google Cast & DLNA/UPnP - Apps on Google Play

 

[Left Channel]

Well Left, your news opens a whole new avenue / freeway of investigation. I am amazed that Tidal would include MQA in their Android app, but not get around to telling anyone about it. No, hang on, I'm not amazed, I am disappointed.

Tidal mumbled something about supporting MQA for the LG V30, but they never got round to clearly mentioning USB output in their own marketing as far as I can tell. I suspect they don't want to encourage millions of new users to buy external DACs and contact Tidal for support.

In the meanwhile and fyi, the technically astute Mr. radamel over at Pink Fish recommends an alternative Android app "mconnect" for streaming MQA from Tidal via Android:

Tidal Masters (MQA) using ChromeCast Audio | pink fish media

mconnect Player Lite – Google Cast & DLNA/UPnP - Apps on Google Play

Interesting! MQA over UPnP. I find his first link most useful: http://www.conversdigital.com/eng/product/product04.php

 

[Mark Dirac]

Well Left, your news opens a whole new avenue / freeway of investigation.

So here's what I find:

Tidal app for Android
Will not play MQA. Will not light blue or green MQA flags on S2D. S2D reports sample rate as 96kHz whether I am playing a non-MQA/Masters track, or whether I think I probably am playing an MQA/Masters track.
But, I have to say, Tidal's UI in their Android app is pretty smart and nice to use, even though some of the features are completely counter-intuitive, difficult to find, and completely undocumented. But I reckon that after 6 months of this iteration of their UI, I have now found out how to use it to its full extent.

UAPP app
This works. It didn't work at first. There was a lot of stuttering, and then I noticed that sometimes during a stutter, the S2D's blue MQA flag lit. So I searched for the possibility of a "bit perfect" option, found it, selected "hardware volume control", and lo! success.
But, I have to say, UAPP's UI for Tidal is pretty naff.

I wonder how UAPP and mconnect are doing this? Are they hacking the normal Tidal UI, or has Tidal developed some interface or API for third parties such as these folks. If the latter, then I am surprised, given the paranoia about having hi-res files pirated.

Finally, and most importantly, how does it sound? Well, that will take me many more hours to decide. I would be very surprised if MQA over Android into an S2D sounds worse, or even different, to MQA over Windows. I will report back.

Equipment: LG G6 connected via otg to S2D with wall wart connected. LCD-3 headphones. Tidal "HiFi" subscription.

 

[Left Channel]

So here's what I find:

Tidal app for Android
Will not play MQA. Will not light blue or green MQA flags on S2D. S2D reports sample rate as 96kHz whether I am playing a non-MQA/Masters track, or whether I think I probably am playing an MQA/Masters track.
But, I have to say, Tidal's UI in their Android app is pretty smart and nice to use, even though some of the features are completely counter-intuitive, difficult to find, and completely undocumented. But I reckon that after 6 months of this iteration of their UI, I have now found out how to use it to its full extent.

It will pass a decoded signal out of the LG V30 and the Essential Phone. Something odd happens on other phones when you try to play it via USB. Is your phone volume at 100%?

I wouldn't spend too much time battling with this, not when the Tidal folks clearly don't want to talk about it. When playing through most other Android phones' internal DACs I think even 44.1 tracks get upsampled to 48 kHz, and perhaps that affects what comes out of the USB port as well.

I really have no idea what's going on in there. It's enough to make my head spin.

UAPP app
This works. It didn't work at first. There was a lot of stuttering, and then I noticed that sometimes during a stutter, the S2D's blue MQA flag lit. So I searched for the possibility of a "bit perfect" option, found it, selected "hardware volume control", and lo! success.
But, I have to say, UAPP's UI for Tidal is pretty naff.

I wonder how UAPP and mconnect are doing this? Are they hacking the normal Tidal UI, or has Tidal developed some interface or API for third parties such as these folks. If the latter, then I am surprised, given the paranoia about having hi-res files pirated.

Finally, and most importantly, how does it sound? Well, that will take me many more hours to decide. I would be very surprised if MQA over Android into an S2D sounds worse, or even different, to MQA over Windows. I will report back.

Equipment: LG G6 connected via otg to S2D with wall wart connected. LCD-3 headphones. Tidal "HiFi" subscription.

Everyone seems to go through the UAPP stuttering stumble before finding the bit perfect setting. It probably should be the default or at least offered in a setup dialog.

Tidal and Qobuz do provide APIs for developers. That is how the UAPP developer tags the titles of Tidal MQA and Qobuz Hi-Res albums with "Hi-Res". Apparently that's also how they get the raw MQA signal.

The UAPP Tidal and Qobuz interfaces are based on the categories provided by those APIs, and at this point I'm used to them. As to how it sounds... well, without an external amp, it's still a phone.

 

[Tnewell]

I have been using the S2 as DAC only in my headphone rig. Up until now, I had the volume set at 0 dB using the rca output. I recently purchased the Monolith Liquid Platinum headphone amp which has tons of gain with no switch for low or high gain. This has forced back down the volume on the S2 to -10db so I have some play in the volume on the Monolith amp.

My question is am I losing any resolution from S2 backing the volume down to -10db? Really would like to avoid putting a passive preamp in the chain.

Thanks much!

 

[Mark Dirac]

Someone asked a similar question a while back and John Westlake, the designer, answered that you would be fine and not lose any resolution even with the volume a lot lower than -10dB. JW stresses that the digital attenuator is of sufficiently high precision that no distortion is added. I sort of reckon that this is the meaning of "pre" in "Pre Box S2 Digital" - i.e., the attenuator is good enough for the product to function as a preamplifier.

 

[buson160man]

I bought the pre box after reading positive reviews in both hifi new record review and the absolute sound. Have had the dac since a little bit before thanksgiving. I am in total awe of this mini marvels abilities as both a dac and headphone amp. And it was darn good as a preamp on my desktop as well with my emotiva airmotiv 5 active speakers. This unit is nothing less than a giant killer. At least in my experience. I have a Yamaha cd 2100 player dac and the s2 is much higher resolved. This 400 unit has a much better dac section than the 3000 dollar Yamaha. I will go further this is the best dac I have owned. I have gone thru the teac ud 501 and peachtree deco 2 and this dac is clearly more resolved. II use to have an old theta dac the series IIII and the level of resolve reminds me of my old dac compared to most units I have heard even some expensive ones and this mini marvel comes surprisingly close in more than a few ways. I initially had bought it to replace my peachtree deco 2 which took up a lot of space on my desk top. The s2 was just so tiny and cleared up a fair amount of much needed space. But it turned out to be so good that I am using it in my main rig in the living room tethered to the Yamaha as a transport. I highly recommend this mini marvel to anyone who is looking for a more resolved sound with very little coloration if any. This unit is very honest sounding and fires straight from the hip. Even if you intended to spend a fair amount more on a dac pre headphone amp I recommend you should give the s2 a listen I think you will be amazed of its abilities.

 

[Tex Irie]

Has anyone compared the Pro-Ject Pre Box S2 Digital to the Schiit Bifrost Multibit using the Schiit Jotunheim as an amp? Where there any noticeable differences in sound quality?

 

[zakazak]

So it seems that generally pro-ject has pretty good quality devices?

I am thinking of buying a whole rig from them for my HD800S (DAC, Amp, maybe power supply).
Maybe in combination with a Feliks Elise.

Or should I rather go for another more known brand?

 

[Tex Irie]

I haven't received much input but these pro-ject Devices seem to be well built. I'm debating purchasing one for the DSD functionality to pair with my Jotunheim.

 

[Left Channel]

Has anyone compared the Pro-Ject Pre Box S2 Digital to the Schiit Bifrost Multibit using the Schiit Jotunheim as an amp? Where there any noticeable differences in sound quality?

So it seems that generally pro-ject has pretty good quality devices?

I am thinking of buying a whole rig from them for my HD800S (DAC, Amp, maybe power supply).
Maybe in combination with a Feliks Elise.

Or should I rather go for another more known brand?

I haven't received much input but these pro-ject Devices seem to be well built. I'm debating purchasing one for the DSD functionality to pair with my Jotunheim.

Pro-Ject and Schiit products all offer good sound quality. The difference is in sound signature. In general the Pro-Ject Pre Box S2 Digital and the Pro-Ject Amp Box S2 are very different from Schiit products, with the former being more neutral and resolving, the latter smoother and more forgiving though the multibit DACs are less so.

The Pro-Ject DS2 line, which I have not heard, may be closer to Schiit in sound signature. I suspect the Felix tube amp is warm and forgiving too, simply because of the tubes and because many French products simply sound warmer than most, but I have not heard it either. I'm just a random person posting opinions on the Internet, after all.

Overall Pro-Ject has a good reputation, but you should do further research as some of their DACs have firmware bugs that have not yet been fixed. I do like their modern industrial design. Feel free to ask more questions about the S2D or any other specific model.

 

[zakazak]

Pro-Ject and Schiit products all offer good sound quality. The difference is in sound signature. In general the Pro-Ject Pre Box S2 Digital and the Pro-Ject Amp Box S2 are very different from Schiit products, with the former being more neutral and resolving, the latter smoother and more forgiving though the multibit DACs are less so.

The Pro-Ject DS2 line, which I have not heard, may be closer to Schiit in sound signature. I suspect the Felix tube amp is warm and forgiving too, simply because of the tubes and because many French products simply sound warmer than most, but I have not heard it either. I'm just a random person posting opinions on the Internet, after all.

Overall Pro-Ject has a good reputation, but you should do further research as some of their DACs have firmware bugs that have not yet been fixed. I do like their modern industrial design. Feel free to ask more questions about the S2D or any other specific model.

Thanks for your reply.

Well basically I am interested in the DAC Box DS2 Ultra together with the Head Box DS2 B.
And then maybe also the power supply in the fitting form factor.

Its a lot of money and I could go with a ragnarok + multibit bifrost instead. Or maybe something else.

So I really want to make sure that their stuff is decent. I have read reviews of their other stuff and it seems like they are kinda mid-tier? And firmware bugs doesnt sound very promising either :/

 

[Left Channel]

Thanks for your reply.

Well basically I am interested in the DAC Box DS2 Ultra together with the Head Box DS2 B.
And then maybe also the power supply in the fitting form factor.

Its a lot of money and I could go with a ragnarok + multibit bifrost instead. Or maybe something else.

So I really want to make sure that their stuff is decent. I have read reviews of their other stuff and it seems like they are kinda mid-tier? And firmware bugs doesnt sound very promising either :/

They are mid-tier of course. What audio products under US $1,000 are not? But the S2 line really punches above its weight, and I would hope the DS2 line at more than twice the price does so as well!

The S2 and DS2 product lines were designed by different teams. The DS2 Ultra is an AKM-based DAC like the non-multibit Schiits. I saw a couple of DS2 boxes at AXPONA in April, but did not hear them. They were larger than the S2 line, appeared to be of good quality, and had a simpler interface. I notice there is a firmware update for the DS2 Ultra, and that's actually a good sign. There is no update for the DAC Box S2+ and that's a problem, but as I said it was designed by different developer. That developer no longer contracts with Pro-Ject but may yet product a final set of fixes for the S2 and S2+ DACs.

Pro-Ject is still mostly a turntable company and they've hit a few speed bumps on the road to figuring out computer audio, but I have high hopes for the DS2 line and future Pro-Ject projects.