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Pro-Ject Pre Box S2 digital DAC

Discussion in 'audio' started by miero, May 9, 2017.

  1. Antonio

    Antonio New Member

    Greetings to all from Italy, I'm an enthusiast owner of the small S2. Can anyone tell me why, listening to some master albums, the little circle near the MQA symbol on the display changes from blue to green?

  2. lonek

    lonek Member

    • Green logo – MQA valid, the MQA is detected
    • Blue logo – MQA authored, the MQA is detected and the file is fully authenticated. You can be sure you are hearing exactly what the artist approved in the studio
  3. tuga

    tuga Legal Alien

    Apparently "MQA authored" doesn't always mean that it was approved by the studio.
    Google Brian Lucey and MQA.
    Julf likes this.
  4. gahabana

    gahabana Active Member

    @JohnW ,
    thank you and Jacek on 2.12 firmware fix. Did make all the issues disappear in PCM and DSD via DoP formats.
    However, now I am certain as there are other users on Linux when using S2 DAC in Native DSD mode, when there is switch from 44.1 PCM or 176.4 PCM to DSD64 there is noise that starts about 1-2 seconds into DSD file and disappaers after 7-8 seconds. Pausing playback does not help - as if DAC is going through some old buffer of data ...
    Is there any chance this could be looked into ?

    Thank you !!!
  5. JohnW

    JohnW pfm member

    This is NOTHING to do with the DACs operation - we have no such buffer... What does the DAC display indicate? this will give a clue as to what might be happening.

    Linux support of DSD is hysterically stupid - Linux does not follow the industry "standard" and requires each individual DAC to be added to a device table identifying its DSD support.

    We have streamers projects in development built around Linux and have no issues with NativeDSD so I'm pretty sure its not the DAC at fault.
  6. gahabana

    gahabana Active Member

    hi @JohnW
    You're right on Linux being 'stupid' requiring DAC to be recognised by kernel ... but that was added to recent kernels and there are few dozen of DACs that work under linux with DSD in Native mode. S2 does work in Native mode as well with exception of that 2 scenarios when problems occur. Verified on Raspberry Pi , Odroid C2, Odroid XU4 and NanoPi Neo and am sure intel/pc would be the same as kernel is shared.
    I have shared that info (that DAC S2 DOES work in DSD Native mode with recent or updated kernel) here:

    Would be great if you can try on your Linux streamer - all you need is one PCM 44.1 file and one DSD64 and am sure you will be able to replicate the issue. MPD as player or Squeezelite or Roon Endpoint. If you get a different outcome - I would love to hear about it !

    But to answer your question - Display on S2 immediately switches to DSD64 ... here is the link to video i've just taken. I apologise for hiss but it's because i made recording on crappy phone AND because when it moves from the PCM song to DSD hiss/noise is very loud - but you will notice it. Switch happens at 44 seconds into the clip.

    Thank you !!!
  7. Julf

    Julf Facts are our friends

    Have you discussed it with the developers?
  8. ajs6000

    ajs6000 Member

    Hi all,
    I've just order this DAC and would like to know if I could use a data only USB cable for the digital input and a power only USB micro cable for the 5v power supply?
  9. left channel

    left channel Prominent Member

    Yes. The manual is incorrect in saying that you should not connect both at the same time. In fact, the designer recommends doing exactly that for better sound quality. The manufacturer hopes to revise the manual soon. The product comes with a 5v 1000mA switching adapter; I replaced it with a linear adapter.
  10. gahabana

    gahabana Active Member

    hi Julf, well there is not much to be done in Linux. What needs to be done has been done already - Linux kernel 2 months old or newer knows that Pro-Ject DAC S2 can do native DSD. It is Pro-ject who need to test it shoud test it and if/when they do they will figure out something is not right. I think there are 3 options - fix the firmware (easiest), write the linux driver (lot of work) or do nothing.

    I don't know if Pro-Ject reads these forums nor if they want to do anything about it ... @JohnW and his colleague were designers but they are not employed by Pro-Ject ... so i think they are the ones who would KNOW how/what to do but real question is - do they have any motivation for few dozen people who would like to run Native DSD ... and truth is that DSD64/128/256 work perfectly via DoP so the only real benefit is bringing dsd512 which is possible only in native mode and that DOES work. The downside is that in that case if you do not upsample everything to dsd512 you get these issues when switching from pcm 44.1 and 176.4 to native dsd64
    Julf likes this.
  11. Julf

    Julf Facts are our friends

    Right - I was thinking about the larger architectural issues JohnW referred to when he wrote "Linux support of DSD is hysterically stupid - Linux does not follow the industry "standard" and requires each individual DAC to be added to a device table identifying its DSD support".
  12. Fred Abrams

    Fred Abrams Member

    sorry, this was probably covered but just got the box for Xmas. downloaded driver and firmware update and it plays however no blue light or logo when playing mqa files from Tidal. Any help appreciated. Merry Christmas.
  13. dreamword

    dreamword New Member

    In the Tidal desktop app, in Settings, go to the Streaming tab and make sure Quality is set to Master. Then under Sound Output; select your output device; then click on the gear icon that appears when you mouse-over the output device name. Check all of the boxes (Exclusive Mode, Force Volume, and Passthrough MQA). Working now?
  14. Fred Abrams

    Fred Abrams Member

    got it! had force volume instead of exclusive mode
  15. JohnW

    JohnW pfm member

    I'm not sure your correct here - I understand from the Roon forum that the S2 works for you correctly under Windows? and it works for us with Linux with customized OEM versions of Volumio, I'll double check.

    However, IF it works for you with windows then this REALLY points to a Linux issue as the DAC has no care about the OS used - only the Data it receives.
  16. JohnW

    JohnW pfm member

    Yes, the Linux community really needs to sort this out, we can advise what needs to be done to "standardise" Linux DSD support with the rest of the industry. It appears that whoever added DSD support to Linux was unaware of what has become the defacto "standard".
    Last edited: Dec 27, 2017
  17. JohnW

    JohnW pfm member

    To be correct here, the supplied Switching supply (or any other switching supply) SHOULD NOT BE USED at the same time as USB power due to high Earth Leakage currents.
  18. left channel

    left channel Prominent Member

    Thanks John. We had gathered from one of your previous posts in this thread that the user manual is wrong: attaching the supplied switching supply improves the sound quality over USB power alone, and that is why you implemented an automatic change from USB power to external power when an adapter is plugged in. Are you saying switching supplies are to be avoided, but linear supplies are OK?
  19. atomic garden

    atomic garden Member

    Hello guys. 1st time poster here. First, thank you all for the effort, specially @left channel. I almost created my account as "right channel" as a reverence :)

    I would like to add to the question: Even using a data only USB cable (5v pin disconnected), a switching power supply should be avoided?
    Mark Dirac and left channel like this.
  20. JohnW

    JohnW pfm member

    Yes - in the best interests of sound quality avoid a switching PSU under any condition.

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