Best digital interface

March 29, 2021
 by Paul McGowan

22 comments on “Best digital interface”

  1. You might change your mind about USB being your least favorite method if you used a Revelation Audio Labs Prophecy CryoSilver™ Reference DualConduit™ USB 2.0 Digital Link cable which has been burned in for about 1000 hours.

  2. I got much better sound from Roon on my computer by switching from the Bridge II input on my DirectStream DAC to the USB input. My computer is 15′ from my DAC, and the USB run is intermediated by two hubs. The last hub before the DAC is actually a good USB reclocker (Ciunas Audio). Among other things, there was a dramatic improvement in bass tightness and extension. So I think the ability of an interface to accept an inline reclocker could be important, which says something about the design of the DAC or maybe the Bridge II card.

    (In my obscure case, the choice of inputs is critically dependent on how well they work with the wetware in my brain. It killed me to have to revert to the Bridge II after two nights of listening, but I had to because my hearing has become sensitive as I’ve aged and the USB feed gave me tinnitus – which I’ve still got months later. This ‘wetware interface’ is the overriding consideration, bar none, which I’ve struggled to understand for over a decade. I’m glad the DSD offers different input types for me to experiment with.)

  3. There are no measurable (or with the capacity to hear it) problems with USB. Modern DACs have no problem with USB, neither do good computers. And a cheap USB wire is good enough.
    Spend the money in speakers.

        1. Which ones don’t is a better question. When I write “dirty” I mean noise-filled. If you have a chance, grab a scope and have a look at the 5V bus coming out of any computer. It’ll be obvious to you immediately. Computers are quite noisy environments. If you don’t have access to a good scope there’s another way you can find out, by using an AM radio tuned between channels or even one of those live AC checkers (that basically use the same AM receiver). Bring them in close to the computer or the unterminated end of a USB cable and watch what happens from the radiated noise.

  4. What can we say about synchronization using these different interfaces? If I understand correctly, with I2S the bit clock is generated by the transmitting end (for example, the CD transport). S/PDIF is the same. With USB, there is an option for the transmitting end to generate the clock (synchronous mode) or for the receiving end (for example, the DAC) to generate the clock (asynchronous mode). In the USB asynchronous mode, the DAC is able to request the sending end to increase or decrease data rate so as to keep buffer depth within set limits.

    I would have thought that the USB asynchronous mode would be the optimum scheme, because it allows for a stable, free-running, low jitter clock in the DAC. Have I got that wrong?

      1. I would be interesting to understand how that works. The straightforward approach would be to regenerate the I2S clock in a phase-locked loop (PLL), and use this to drive the DAC. I’m not sure how the Directstream DAC would prevent buffer overruns/underruns if it simply disregards the I2S clock.

  5. I’ve built a music server that’s been highly optimized (as best as I can, with my current knowledge and understanding)for the playback of audio. That’s it’s only job. When deciding upon components I should build it with, I choose to install an I2S bridge from Pink Faun in the Netherlands. I’m using an Audioquest Vodka HDMI cable to connect this PC to my PS Audio Directstream DAC. I couldn’t be happier with the results, as it sounds fantastic.

    There are many ways to improve upon the sound coming out of a PC/Audio server including the use of an external linear power supply (LPS) (which makes a huge difference), the type of wiring used internally for power connections (I’m using 15.5AWG Mundorf Silver wiring in as short of lengths as possible (not just because of it’s high cost) for the power connections from the LPS to the 8 pin and 24 pin connections on the motherboard), a fanless cooling design for the enclosure that uses copper heat pipes to transfer heat away from the CPU, an I2S card from Pink Faun (which has an upgraded clock also from Pink Faun),specialized RAM,and playback software (Euphony). I participate in a forum for audiophiles that chases bleeding edge tech and ideas for improving sound coming from PC, and have built several examples as a hobby in my spare time. The ones using the I2S interface sound the best in my humble opinion.

  6. I’ve probably learnt more about this topic over the last year or two than I have in prior decades as a computer professional and audiophile. Probably because in retirement I can spend more time considering such things! 😉 It’s mainly been by listening to and reading the words of people like Paul and others who have greater technical knowledge than I on such matters. Becasue of this and with experimentation in my own system, I’ve found that I2S does sound the best, at least in my set up.

    As can often happen with quests, I didn’t start out particularly looking for the ‘best’ digital interface. I have a DirectStream DAC which began it’s life as one of the original PerfectWave DACs. (The chasis, at least, is still the original! 😉 ) At any rate, I was using 3 digital inputs, USB, Toslink and the Bridge and was looking to somehow consolidate them into a single input. I also started looking at content recorded in DSD format. I can remember Paul talking about how I2S was the best input for the DAC even back then and how it could handle PCM and PDM bit streams. Using the I2S input appeared to be the best way to achieve my goal.

    An important discovery I made during my journey was the importance of galvanic component isolation. Ideally you need to get a bit-perfect bit stream into the DAC’s input. The digital processing steps to achieve this are relatively easy. However, an unwanted product of the processing effort can be distortion of the timing signals that govern the bit stream’s ultimate delivery and rendering.

    My understanding is that the DS DAC ignores the timing signals and determines the bit stream type and rate by other means. Nonetheless, many of us believe that the bit stream can already be damaged by the time it gets to the DAC and subsequently affect the sound quality.

    In summary, I believe you should by all means choose the input which satisfies the digital format requirments of your chosen source content but expend your greatest effort on galvanically isolating the DAC from noisey sources. I’ve found the ‘best’ way to do that is by using the I2S input.

  7. If people ever ask me that “ what is the best digital interphase “ I’m gonna tell them to buy a cd transport, a quality DAC and an amplifier. Call it a day. Lol.

  8. The best digital interface is no interface at all. I’ve yet to hear a good reason for having a streaming source and DAC in a separate box separated by a wire. For the last 12 years they’ve been in the same box other than when I had a PS Audio DAC (3 years).

  9. Mcintosh Blue Rae player, connected to a Mcintosh dac via HDMI cable if you’re looking for a grate SACD/DSD playback.
    And yes, you can take this same dac, and plug it in to one of the USB ports on your computer without any problems!
    I don’t remember this too much, but I do believe that Mcintosh uses a quod of 12AX7 tubes on the analog output of that dac.

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