DoP

November 3, 2022
 by Paul McGowan

The three-letter acronym, DoP has a number of meanings depending on what you're interested in.

To the Italians, D.O.P. stands for Denominazione di Origine Protetta (Protected Designation of Origin): the name used to indicate a product that owes its characteristics to its place of origin, and its production, modification and processing occur within that geographical area. Bubbly Champagne from Champagne France, and tasty Modena vinegar from Modena Italy.

For Audiophiles, DoP stands for DSD over PCM. Playback Design's chief digital guru, Andreas Koch, invented DoP as a means to allow DSD to be compatible with computers not possessing the means to deal with it.

A good (short) video on the subject is one our own Gus Skinas and I put together in my older series called Lunch with Paul.

DoP has a marketing problem. The mention of it has many purists running for the hills. Why? Because it is assumed DoP converts DSD to PCM, thus changing forever the characteristics of DSD we all love.

Two things are wrong with this. First, DSD is not being converted to PCM. Second, even if it were, there's no sonic penalty when done correctly (though in their defense it rarely is).

Today's computers don't know what to make of DSD. Without a special driver and program installed, a Windows or Mac computer sees DSD as unrecognizable noise. This is because DSD is very much like analog: a continuous unbroken stream of moving data that can be directly listened to as music. PCM, on the other hand, is made of discrete chunks of data each with its own ID that serves as a routing map.

What Andreas did was really clever and simple. Instead of trying to fit a square peg (DSD) in a round hole (the computer), he simply broke the continuous DSD stream up into discrete chunks and added an identifier bit that serves as a routing map. To the computer, DoP looks like PCM and it merrily passes it along to your DAC.

When your DAC gets this "PCM-like" stream of data, it knows to remove those added identifier bits and reassemble the unmolested virgin DSD bits back together so we get that analog-like continuous data stream called music.

The DSD data is identical to its beginning. It was never converted to another form.

Hope that helps.

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38 comments on “DoP”

  1. Andreas Koch's Playback Designs - 'MPD- 8' aka 'Dream DAC' (AU$37,500) is a
    DAC that will eat all other DACs for breakfast, including the MBS - 'Reference'
    DAC (AU$55,00) & the dCS - 'Vivaldi' DAC (AU$47,995)
    But if these prices are a little out of your current home-audio budget then you
    can purchase a great PS Audio - 'DS Mk2' DAC for only AU$14,000 😀

  2. Just to clarify, France is not in Italy and in France they use AOC (appellation d'origine contrôlée). Plus, Balsamic comes from Modena (no R). Moderna is a US Pharma company, and their stuff doesn't taste half as good.

    Never heard of DoP. For my 5 DSD files, my server says it does Native DSD and for DSD128 and DSD256 it can do "DSD over PCM", which would be nice, but my handful of files are DSD64. It also gives the option "Transcode to FLAC".

    So maybe Innuos decided an acronym was unnecessary for those who "love" DSD (not me). I don't have an amorous relationship with data.

    Personally, I like AOC (analogue over copper) and a glass of Chateau AOC to go with it.

    1. Just to clarify, if you bought a sparkling Italian wine it would be DOC, not DOP, so Paul is comparing chalk and cheese. DOP applies to food (especially cheese) and DOC (denominazione di origine controllata) to wines and spirits. DOC and AOC are national law. DOP and AOP (appellation d’origine protegée) are European law.

      I put this down to the American allergy to regulation, with notable exceptions, I suspect Europe can out-regulate and out-acronym anyone.

      1. Bear in mind that the provenance and purity of food and wine for those of us who take our holidays in Italy and France is rather more important than the provenance and purity of digital audio signals. I suppose it depends on your priorities. Mine are gastronomic and oenological.

  3. This is very well explained and of course a bit of a complex issue.
    I like the explanation of “not trying to fit a square peg into a round hole.”
    That alone allows me to see and understand how the data stream works, is presented and recognized by a computer.

    Thank you, Paul. I never saw it this way.

      1. Appreciate you very much. Definitely talk soon and I love my Octave Records recordings. Simply delightful and exemplary fidelity.
        Gonna be adding more octave releases to my collection in the future for sure. Keep it going, sir! Well done!

  4. Is the enormous increase in storage space on my HDD for quad-DSD-files or high-res PCM-files compared to RBCD-files really justified when there is finally no audible improvement the in sound quality? And why aren’t there dealers or sales-guys on HiFi-shows who regularly perform high-res demos for proving the superiority of specific audio components? Maybe there are huge advantages for recording and mastering (head-room) but the majority of sound-engineers I know never claim that their high-res mixes sound better than the downsampled RBCD mixes on home audio systems - even not on headphones. Today the majority of stereo audio demos are based on streaming via Roon! And yes, I detect differences in sound quality with different Ethernet hubs or different cables but no differences between highres and 16/44.1.

    1. Off to hear the European launch of the Wilson Alexia V tonight (that's the listing, even if UK not in the EU). I've never known my dealer to use DSD.

      Using Roon has the real advantage of effectively unlimited storage (usually using a QNAP or Synology server). My Innuos Zen has 4TB with SATA drives that make a little bit of noise (doesn't bother me). The Zenith that PS Audio have use SSD that needs an additional internal linear power supply because SSD is very electrically noisy (so Innuos tell me). Some people have retro-fitted SSD into Zen to save a few $ over a factory upgrade and it actually makes performance worse.

      So these massive DSD files or big libraries need a bit of storage planning. Roon recommend using the QNAP TS-473 (I have one, not because Roon recommended it, it's the most popular 4 x SSD QNAP) with 2 x 2TB SSD + 2 x 8TB SATA discs. It makes a lot of sense and is not that expensive.

        1. Well, I arrived late and Mr McGrath was struggling with his laptop, which was plugged into dCS Vivaldi Apex. My dealer was joking he should have stuck with vinyl, because there was a reference Vertere/RCM system plugged in. The little I heard was impressive, and even though it was running overtime I had to leave to go to a recital, which was excellent. I parked outside their front door and as I walked past 2 hours later after my concert, they were packing them up, so I suspect they are doing a road trip. The rest of the system was DartZeel pre and power and Shunyata Denali.

          Being mid-price for Wilson, I suspect my dealer will shift quite a few pairs. Quite modest for some of their clients, the guy next to me was going on about a pair of MC2301 he'd ordered for his dCS Viv and SF Aida.

          1. Well I’m glad you made it. Sounds like a meaningful experience.
            For the record. I love DCS. I think there terminator and Bartok DACs are exceptional. Of course the Rossini and Vivaldi are on another level.

  5. Paul

    I now understand how the data stream is passed on by the computing device. One quick question: How does the DAC distinguish the DSD over DoP from PCM?

  6. Paul,
    Taken from paragraph six.
    “First, DSD is not being converted to PCM. Second, even if it were, there’s no sonic penalty”
    No sonic penalty. Is it therefore fair to assume that PCM can sound as good as DSD? Or is that only the case if it starts out as DSD?

    BTW, like Nephilim 81, I also found it a useful and helpful explanation today. I don’t always delve that deeply into the technical details although they can be interesting. I’m a firm believer that the greater knowledge we have helps us make more informed and therefore better choices. Sometimes learning one new piece of information can completely alter a perspective.

    1. Thanks, that's very kind.

      If we start with DSD then properly low pass filter it to get to PCM has almost no penalty. The opposite is not true.

      I like to think of it this way. Imagine a crappy phono cartridge versus an amazing one. If you start with the crappy one (PCM capture) you are likely to never get all that is on the disc sent through your system. Thus, no matter how good your electronics are, if you cannot get the info off the disc there's nothing you can do post playing the record.

      Now use the excellent phono cartridge (DSD capture). You gotten all there is to get and you're better off down the electronic chain even with lesser equipment.

      I have an upcoming post about this that may shed more light.

  7. Paul, You credited Andreas Koch of Playback Designs with inventing DoP. At an audio show in NYC quite a few years ago the guys from dCS were handing out leaflets that made it seem like they invented DoP

    I tried to google search to find out who invented DoP with no luck. I could barely get google to understand what DoP I was searching for. Is there any place online that has the history of DoP?

      1. DCS claim to have invented the concept for DoP. The listed authors of the original open source standard are Andreas Koch, Andy McHarg (dCS) and Rob Robinson (ChannelD).

  8. Paul, I'm confused. In your original post you said "The DSD data is identical to its beginning. It was never converted to another form."

    But then here you say "If we start with DSD then properly low pass filter it to get to PCM has almost no penalty."

    Which is it?

    Is DSD converted to "get" PCM or not? Does it have "almost no penalty" or is it "identical to its beginning"?

  9. If I had a dollar for every time I had to explain to folks that there is no sonic downside to using DoP vs Native DSD I would have very many extra dollars! There is one potential downside to consider though, for those who like to playback very high rates of DSD. One can now get recordings made in DSD 256 and even recordings oversampled (using the incredible modulators/filters of HQPlayer pro) to DSD 512. With the right DAC these high rates of DSD can sound fantastic. But to playback these rates with DoP requires a DAC which can handle 705.6 kHz PCM for DSD 256 and 1411.2 kHz PCM for DSD 512, so that is a limitation.
    The time for needing DoP has mostly passed, as there are plenty of source components, like those streamers (I prefer to call them renderers) from Sonore, which handle native DSD up to DSD 1024, and can serve those rates out to a DAC via USB. The latest XMOS USB receivers can handle up to DSD 1024, Native, with the right code, so there really is no more need for DoP anyway, and I would encourage all DAC designers to set up their DACs to be able to to process and receive these high rate DSD streams.

  10. The obsession with DSD was another chapter of this audio journey. I got all caught up & morphed into Captain Kirk (Must…… find it…..in….. D…….S……..D….DSD!) It became the trophy wife of music. “I got that in DSD!” And like that trophy wife, it was EXPENSIVE!

    After sourcing out several of the (relatively few) older albums available in DSD, the sonic improvements over the originally were often merely meh. Now, newly recorded stuff in DSD stuff is fantastic, but the thrill of the chase for the hottest available format has subsided. If DSD is available, I’ll certainly opt in, but if not, I will live on. The ….must….hear….DSD….gives way to I just want to hear this song.

    DSD was a good relationship and we still hook up from time to time and it is great (some nights it’s just DSD tracks - all-night-long) but the lust for do-all-end-all gotta-have-it-in-DSD-now has waned. I’ll make do and be content with hi-res, wav, flac, or yes even mp3. Yet sometimes still, if I’m in chorus deep into a hot track, I’ll drift off and secretly think to myself “hmm, if only I could get THIS in DSD….sigh”.

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