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Pro-Ject Pre Box S2 digital DAC

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

  1. left channel

    left channel Prominent Member

  2. DimitryZ

    DimitryZ pfm Member

    Looks really bad...I no longer use it for MQA duty, but it really should be fixed.
  3. left channel

    left channel Prominent Member

    The solution is to not use the Optimal Transient filter. After much testing of this box, the developer of HQ Player recommends the Fast Rolloff filter for best results anyway (and also recommends enabling Distortion Compensation). I don't know if we'll ever see a bug fix.
  4. skanderborg

    skanderborg Member

    I measured the noise spectrum of the included switching PSU in audio band. In comparison with mine DIY PSU here:
    (Both PSU measured with output load 10 Ohm, i.e. output current 0.5 A).
    Included PSU is really very bad.
    My own DIY PSU is very simple (2x Li-Ion accu plus Analog Devices ADM 7150 extremely low noise linear stabilizer), but very clean.
    S2D sounds significantly better compared to USB supply.
    For inspiration my PSU here:
  5. skanderborg

    skanderborg Member

    I did a DXD vs DSD128 listening comparison.
    My listening set: S2D powered from the clean battery PSU, filter "Fast Rolloff" + Sennheiser HD600 headphones.
    I used recordings from 2L.no (2L-038_stereo_FLAC_352k_24b_01.flac vs 2L-038_stereo-DSD128_01.zip = Mozart: Violin concerto in D major).
    From my SUBJECTIVE assessment, DXD (i.e. PCM 352 kHz/24bit) sounds better than DSD128. DXD has little more space, air and contains more small details.
    The biggest difference is in spatial separation of solo violin, which is better separated from the orchestra.
    Does anyone have a similar experience?

    For you interest, I measured the frequency spectrum at the S2D output for the 1 kHz sine/-40 dBFS (PCM vs DSD).
    The result is here:
    microtone and atomic garden like this.
  6. microtone

    microtone New Member

    I think that this recordings from 2L.no can´t be used to do a proper listening comparison between DXD and DSD128, because 2L record and master in DXD, and then convert to DSD128. So the DXD file will always sound a bit better, because it was the original, and the DSD128 in the better case can sound the same if the conversion was made transparent. I think that the difference in "space" you and I are hearing are due to this format conversion.

    In this topic: https://audiophilestyle.com/forums/...professional-recording-studiosjaprs/#comments
    user Bunpei, explain about a Reference recording in multi formats released by Japan Association of Professional Recording Studios(JAPRS), that recorded the same performance in various audio formats to provide "a kind of reference standard sources" for professional engineers to recognize actual differences on sound characteristic depending on formats.

    In this JAPRS recordings and many others, I can hear sound quality getting better in this order: 48k/16 < 96k/24 < 192k/24 < 384k/32 < DSD128 < DSD256 which is the best sounding file.
    My listening system: S2D powered by the included switching PSU, Adam Audio A5X + Adam SUB7.

    Your DIY PSU is very interesting! How did you source/made the ADM 7150 stabilizer complete module?
    skanderborg likes this.
  7. skanderborg

    skanderborg Member

    The electrical schematic of my PSU is here:
    The mechanical construction is very simple, all SMD components are soldered directly to the sheet metal base and appropriate pins of the stabilizer without using a printed circuit board.
    (The exposed ground pad of the ADM 7150 must be perfectly soldered to base for proper cooling!)
    The PSU input is powered by two Li-Ion accu in serial.
    atomic garden likes this.
  8. atomic garden

    atomic garden Member

    I would love to test this PSU, but any electrical DIY is currently impossible for me.
  9. sberry20118

    sberry20118 pfm Member

    What software and device are you using for MQA?

    This MQA bug disappears when your software does the 1st 'unfold' and the DAC does the rest (rendering)... and you see MQB on the DAC's display.

    The bug is only there when the DAC does the both decode and rendering.
  10. DimitryZ

    DimitryZ pfm Member

    I use for a niche MQA duty - Nugs.net IOS client allows for MQA encoded live shows to be decoded, but i am not sure who does what - its not transparent to the user.
  11. Jumpwired

    Jumpwired New Member

    Is no one using MQA decoding with this DAC?

    I based my purchase on this forum and another one. There was an earlier mention of the problem, but it seemed fixed.

    The problem is NOT fixed in 2.12 Firmware update. The last promised update never came.

    I am having constant MQA drop outs. 70$ USB Cable and LPS doesn't matter.

    There goes 500$. As much as I want to like this product, it feels totally half-baked with its broken MQA decoding.
  12. DimitryZ

    DimitryZ pfm Member

    Hi, I am sorry this is happening.

    I used it with Tidal MQA and it worked well. Addition or subtraction of any USB noise reduction device inline with the DAC may improve faulty MQA performance.

    Does it work fine with non-MQA USB material?
  13. left channel

    left channel Prominent Member

    I have experienced the same problem from time-to-time. 2.12 greatly reduced but did not eliminate the drop-out problem: this DAC is still more sensitive than most to imperfections in an MQA signal, and unlike competing products it does not fall back to an undecoded format when it cannot get a lock. @Jumpwired I look forward to seeing your reports if you try any of the suggestions you're getting here and on other forums, such as improving MQA performance by adding a USB clean-up accessory, or settling for MQB.
  14. kris1964

    kris1964 New Member

    Witamy. Problem Dac z odczytem plików MQA znajduje się po stronie pływów (dokładnie - dostawca materiału audio). Okazało się, że wydanie starych albumów, popu, rocka, klasyki itp. Jest w porządku. Nowszy (a jest to w większości rock i pop) jest problemem dekodowania. Napisałem do Tidal z interwencją, ale powiedzieli, że wina leży po stronie dystrybutora. Pliki audio z dysku twardego są w porządku
  15. Jamie

    Jamie pfm Member

    (according to Google Translate)
    Welcome. Dac problem with reading MQA files is located on the tide side (exactly - the supplier of the audio material). It turned out that the release of old albums, pop, rock, classics, etc. It's fine. Newer (and this is mostly rock and pop) is a decoding problem. I wrote to Tidal with the intervention, but they said that the fault lies with the distributor. The audio files from the hard disk are fine
  16. DimitryZ

    DimitryZ pfm Member

    There could be something to that...

    I listen to Nugs.net, which streams live concerts, some in MQA. Recently i noticed that my M2Tech DAC displays 96k PCM and not 96k MQA.
  17. kris1964

    kris1964 New Member

    I am convinced. If the problem occurred accidentally, I understand, but listen to Billy F Gibbons - The Big Bad Blues (MQA) - first track at the end of the problem, and the next one more interesting. By repeating this album, the problem occurs in similar places
  18. left channel

    left channel Prominent Member

    When Qobuz learned an MQA album submitted by a supplier was causing problems with the S2D and other DACs, they took it down. When Tidal learns of MQA problems, they just blame someone else and leave the problem in place. Now admittedly the Qobuz apps do not support MQA, and most Qobuz customers don't support it either, but it seems to me this is still a good comparison of responsiveness to customer concerns.
  19. Viktor

    Viktor Well-Known Member

    Dear S2 pro users,
    Does anybody of you know why my DAC (the same one as in this particular thread, in my case connecting my iMac through USB and iFi iCan through RCA interconnects) suddenly began to be more quiet, I mean both channels are working, however sound is hardly heard, there is music but even on maximal volume the sound is not near being loud as yesterday. It’s the same on RCA as well as on headphone output.
    Is it some software glitch or I lost my dac?
  20. left channel

    left channel Prominent Member

    More likely a software glitch, but I can't help with macOS. I do know there are many things you can do to improve the audio coming out of a Mac, but it will fight you every step of the way. :)

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