I2S vs Coax

Why is I2S better than coax? I am currently using a single crystal pure silver coax between my Perfectwave transport and Directstream dac. The sound is spectacular. I am getting a Wireworld Platinum Starlight 7 HDMI cable in a couple of days and I am wondering why the Wireworld will sound better. I am assuming that using the I2S inputs should sound better but why?

I believe the primary difference is the I2S clock is separate and the HDMI cable has excellent grounding. This may or may not make any difference to the DS in your system.

Try it and let us know what you find. It may not sound ‘better’ for a few days or more.

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Ted has stated that he worked hard to make all the inputs sound as good as possible on the DS and I find he was successful. There is not as pronounced a difference between I2S and AES/EBU between my DMP and DS, which are the two inputs I’ve used most often, when they are playing the same content. The difference was far more pronounced in I2S favor when using the PWT and PWD.


Based on my ears, the I2S input does sound better than the USB input. I don’t care about the other inputs as they do not support DSD128 or PCM 352.4

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Lonson. Do you run both the XLR and the I2S at the same time or do you plug in one or the other? I am actually using a single crystal silver RCA as I wait for my Wireworld Platinum 7 and the sound is truly spectacular.

Speed-racer. What is your source?

sonicTransporter i9 -> ultraRendu -> Matrix SPDIF 2 -> DirectStream

I’ve done both. I used a Van De Hul AES/EBU for a while in place of the AC-12 HDMI. There was not a lot of difference betweent the two inputs and cabling. Now I run both I2S inputs with AC-12 HDMI–one for the DMP, and one for the NuWave Phono Converter.

I heard Paul mention somewhere I2s is an interface where the bus separates clock and serial data signals with different wires and is superior to the other interfaces. The proof is in the pudding. I have played around and experimented with all kinds of different cables and played with all the other interfaces on the DS and yes, the I2s outperforms the USB, CoAxial, XLR, and Toslink in my system. With the DMP, it is simple to try the different interfaces, but with the server, I needed to add the Matrix 2 to use I2s to the DS. I also tried the different outputs from the Matrix and I2s still is superior. Finding the best HDMI cable for this link is the way to go if you’re looking to get the best sound you can from the DS.

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Waynanchen11. I am expecting a Wireworld Platinum Starlight 7 HDMI cable in a couple of days. I hear good things about that cable. I am currently using an Audio Art pure single crystal silver Statement RCA cable and I’m getting the best sound I have ever experienced so far in my life! The Wireworld will be fun to try. It’s a pricey cable also pure silver but I don’t know if the silver is the same quality as the Audio Art.

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You won’t be disappointed. The WW PS7 is about as good as it comes. Very neutral natural detailed sounding cable. Only cable I found better in detail is the Revelation Audio HDMI, but takes a long time to get and a bit frustrating for some. For many, the WW is good enough.

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The way the DS works is so different that many standard explanations of why one kind of digital interconnect sound different/better to another don’t apply. Like the part about I2S having separate clocks… in typical DACs that matters, but in the DS it’s irrelevant because the FPGA only ever watches the data – not any explicit or derived clock – to adjust the overall pace of its own master clock.

Ted’s said multiple times that the biggest advantage the I2S inputs have on the DS DAC are the shielding and ground characteristics of the HDMI connector and cable design.


I am curious. Does this mean that any attempt by any device upstream of the DS to accurately clock the stream is irrelevant?

The answer to that question isn’t “yes”, but the benefit you get will be smaller and the reason it has an effect may not be the reason that the product designer was focusing on. Some re-clocking devices may actually make things worse than just connecting your high-jitter Toslink source directly to the DS.

The DS is astonishingly good – though not perfect – at ignoring jitter in the incoming stream. If you hear sound quality differences between different inputs it is mostly because of electrical noise carried in on the wire (a big problem for USB and coax generally), or generated by the input circuitry itself (which seems to be the limiting factor for the USB input and Bridge).

The I2S inputs are very simple, low-noise circuits and the HDMI connector and cable does a good job of not being an antenna. If the I2S source is also very low noise, this gets you a great result from the DS, for reasons not directly linked to clocking.


For what ever reasons I find the Wireworld Platinum Starlight 7 HDMI the best cable so far for my PSAudio Perfectwave transport and Directstream dac. The Audio Art Statement coax cable is wonderful but the PS Audio stuff is meant to sound best with I2S connections.

To be honest in my opinion that is definitely true of the PerfectWave DAC in either edition, but not necessarily with the DirectStrean DAC, which was designed to pass raw DSD over HDMI but otherwise to synch all inputs to one clock and bring all inputs really close to the same sound. I find only subtle differences when I’ve compared.

It doesn’t matter which input you use, or whether you’re playing native DSD or DoP or PCM – the clocking and the jitter rejection work exactly the same way on the DS DAC. There is one clock, and it gets pulled slightly slower or slightly faster as needs be to keep pace with the overall rate of incoming data. That’s it.

No matter which interface is used, the DS does not latch onto any explicit or derived clock signal from the input. All processing and all output is clocked solely from the DS’s own low-jitter VCXO.

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For whatever reason although the new digital pure single crystal silver RCA coax that I recently tried sounds very good the Wireworld Platinum Starlight 7 HDMI cable sounds even better. I would think the I2S through HDMI may have a little to do with it. For whatever reason the WWPS7 sounds better.

A penny’s worth of advice on this…

Give it a couple of weeks for the WW cable to bed in (and you to get used to the sound), then swap back to the coax.
You might be surprised.

Trust your first instinct which one sounds better.

Thanks for the advice. I’LL give it a try for sure. The Audio Art Statement digital rca is a special cable.