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Study: Is I²S interface better for DACs than S/PDIF or USB?

Jimster480

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I2S is without a doubt a better transport audibly, you'll be spending thousands correcting USB before it approaches the sound quality i2s offers, and don't speak if you haven't listen to it less own a dac that has it. Measurements aren't everything but cheapskates will use it as means to avoid all other possibilities out there. Tubes, r2r exists and they are fantastic, but you cheapskates will never understand less buy one.
Cool story bro, your contributions will surely be noted but not taken seriously as they cannot be backed up by scientific fact.
 

Jimster480

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It's the fine details, tight bass and chocolaty mids you see.
I like my mids extra chocolaty. Can't have them get milky like with other inferior transport methods. Superior tech like I2S help to bring the cocoa directly into the mids and you can really feel it sprinkled in there with how full it sounds.
 

BDWoody

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I2S is without a doubt a better transport audibly, you'll be spending thousands correcting USB before it approaches the sound quality i2s offers,

Who convinced you of this nonsense? Do you understand much about the technical side of the hobby?

P.S - I was diagnosed to have an absolute pitch when i was 9, so wouldn't you say that the hearing test is somewhat scientific, no?

No.
 

dartinbout

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No offense, but not everything can be explain scientifically (god ,love Bobby Fischer and so on). I really love this forum, and I have learned quite a lot here, but when it comes to tube,R2R and i2s I have notice that the measurement are not telling the all story. I don't know if one day we will able to explain why, but on many devices that where measured to be lesser than other I heard differently, and so many others. in a blind test I can tell the difference. and in many cases it sounded spectacular. so instead of fighting and being cynical. maybe we could try to join forces to understand why so many people can here something that measurements don't.

P.S - I was diagnosed to have an absolute pitch when i was 9, so wouldn't you say that the hearing test is somewhat scientific, no?
Am I the only one who found it hilarious that fabien32, who has reportedly has "absolute pitch", misspelled the word hear?
 

BDWoody

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Am I the only one who found it hilarious that fabien32, who has reportedly has "absolute pitch", misspelled the word hear?

Not on an international forum. I'm sure I've got plenty of typos in my post history and I'm a native speaker.
 

sarumbear

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Tubes, r2r exists and they are fantastic, but you cheapskates will never understand less buy one.
I respect your beliefs how ever unobjective they are, however I do not accept you calling me, a co-member a cheapskate. There is no place for rudeness on ASR. You are reported.
 

fabien32

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Am I the only one who found it hilarious that fabien32, who has reportedly has "absolute pitch", misspelled the word hear?
first i am not native english speaker. 2. if you read the all post u can see that I spelled it correctly in other places. 3. how a typo or misspelled word have anything to do with the subject?
 

Lupin

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Tubes, r2r exists and they are fantastic, but you cheapskates will never understand less buy one.
Well at least subjective crowd is predictable and consistent.
I was wondering how long it would take for the price argument to come up. Performance is automatically better when a device costs magnitudes more then another cheaper device... heard and seen it a thousand times now. Subjective crowd with their "price is the main performance metric" believe is really the wet dream of every manufacturer.
 

BDWoody

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Jimster480

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maybe you could come with the family to the holy land?
Too much money and work, also traveling is a hectic thing ever since global politics just became a shit show.
What hardware are you using?
I personally have tested i2s with my Smsl xUSB and a topping DX7. I went through a bunch of trouble to make this work just to try it out.
There were no differences I could hear VS my usb setup directly into the DX7.
 

HarmonicTHD

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I2S is without a doubt a better transport audibly, you'll be spending thousands correcting USB before it approaches the sound quality i2s offers, and don't speak if you haven't listen to it less own a dac that has it. Measurements aren't everything but cheapskates will use it as means to avoid all other possibilities out there. Tubes, r2r exists and they are fantastic, but you cheapskates will never understand less buy one.
Haven’t heard so much nonsense for a while. Could you please provide some facts for your audibility claim?
And this it not metaphysics and not even rocket science, so it can be explained by science and facts, provided you understand it or even have facts to back up your claim.
 
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Veri

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I2S is without a doubt a better transport audibly, you'll be spending thousands correcting USB before it approaches the sound quality i2s offers, and don't speak if you haven't listen to it less own a dac that has it. Measurements aren't everything but cheapskates will use it as means to avoid all other possibilities out there. Tubes, r2r exists and they are fantastic, but you cheapskates will never understand less buy one.
You know, this product review here. It's a device that generates an I2S signal out of USB input. To think it somehow bypasses whatever is wrong with USB (spoiler: really nothing), is absurd. PS. I sent in this singxer device to amir who then wrote this article. I have used it extensively. It works well. But no, I2S has no magic properties. Its AES and coax outputs work equally well and without the compatibility mess that are inherent to I2S... o_O
 
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Killingbeans

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Am I the only one who found it hilarious that fabien32, who has reportedly has "absolute pitch", misspelled the word hear?
Having perfect pitch doesn't make you multilingual...

Every time I write something in English, I pray that whatever deity is in the neighborhood will help me minimize the amount of nonsense spelling :D
 
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Piere

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If you suffer from absolute hearing because the notes of your canned music drift in pitch there must be something terribly wrong with your music player. Not with your I2S, S/PDIF or your USB-DAC connection
 

Hernandezt

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Could maybe someone just quickly explain me if the i2s port of my dac smsl do400 is compatible with the Sony UBP-X800M2 using its hdmi output dedicated for audio?
 

antcollinet

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Could maybe someone just quickly explain me if the i2s port of my dac smsl do400 is compatible with the Sony UBP-X800M2 using its hdmi output dedicated for audio?
No. HDMI and I2S are completely different standards. They just happen to use the same connector.

Just use the coax digital ouput. As you can see from the first post in this thread, sound quality will be identical.
 

Philbo King

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This is an analysis of I²S interface to see if it is superior to S/PDIF or USB interconnects for audio DACs. From what I recall, it was PS Audio that popularized I²S for external DAC connections. Phillips (now NXP) had invented I²S years early as an internal protocol to route audio. It was not and has not been blessed for external use over cables. This use has been ad-hoc with no real attempt at any kind of standardization. As a result, schemes for external use vary, some use HDMI connectors, others RJ-45 (ethernet) and so on. Even with the same connector, the wiring may not be the same. You can see the HDMI variation of it here in the devices I tested for this review:


Note that despite use of HDMI connector, there is absolutely no compatibility with HDMI as used in video and home theater. All that is in common is use of the connector or cable, not the language spoken over it.

The motivation for I²S instead of S/PDIF serial bus was to separate the clock and with it, provide some kind of benefit. I let Paul McGowan of PS Audio explain it a bit more:


Toward the end he says I²S sounds "considerably better." Does it? It makes intuitive sense that sending out the clock and data separately would be better but we don't design electronics based on lay intuition. If something sounds a lot better, it better darn show up in measurements and hence this article.

Measurements
I wanted to do this study earlier but lose use of the only DAC I had with I²S input. I am fortunately enough to have the Gustard DAC-X26 with has that input and is one of our top performing DACs. As such, it should be good enough to show any benefit from I²S. I also have the Singxer SU-1 which converts USB to I²S. I just reviewed its functionality in generating S/PDIF. For this test, I will be showing how it performs using I²S.

I started by running my usual dashboard with balanced output of the Gustard DAC-X26 connected to my analyzer and input set to I²S and provided by Singxer SU-1. This is what I got:

View attachment 23901

Usually our oscilloscope waveform display on top left is ornamental and not revealing of much. But here, it immediately shows a problem: the two channels are not locked together! There is a phase shift/delay in one channel and hence the reason the Left and Right don't land on top of each other. I added the phase differential meter at the bottom which shows one channel has a delay of 8 degrees! This is not good. A digital to digital interface better be "lossless" in this regard. And what the heck is the benefit of separate clock in I²S is if it causes this kind of skew?

Maybe our DAC is broken. So let's also connect the S/PDIF cable between Singxer SU-1 and DAC-X26 and measure that:
View attachment 23902

Channels are in lock-step as they should be. We will investigate this further but for now, notice that there is no performance improvement with I²S. Differences are run to run variations.

EDIT: Setting mode switch 6 to on fixed the phase delay.

As it happens, I also have a Gustard U12 USB converter which also outputs I²S. So let's wire that up and see what it does:
View attachment 23903

Ah, channels in lock step as they should be. Performance is the same (again, ignore small changes). So while I²S connection doesn't break anything, it doesn't provide any measurable benefit either.

Since the U12 works better, let's use it to run a jitter test, comparing I²S to S/PDIF on the output the Gustard DAC-X26:

View attachment 23904

Again, we have tiny variations but nothing of not let alone a change that is audible.

Conclusions
It is remarkable how as non-technical audiophiles, we quickly play engineer and decide what is technically better. "Oh, the clock is separate in I²S so it must sound better." Do you even know what a clock is? How about clock skew? How about perils of taking a standard for moving an inch or two inside some gear and making it travel dozens of inches externally? You think that doesn't do anything bad?

If you want to use lay assumptions, think of how S/PDIF is decades old and by now, folks have figured out pretty well how to extract the clock out of it and deliver excellent performance. Such is the case here. S/PDIF has universal compatibility to boot which I²S does not have.

So Paul McGowan, please don't spread misinformation about I²S sounding better. Start by showing us measurements that demonstrate anything improving and if so, why PS Audio gear doesn't have good enough S/PDIF performance to need something better. And then, point the camera at yourself, connect both inputs to your DAC and have someone else switch inputs and see if you can tell the difference. Since levels don't change, it is dead simple to conduct a blind test.

Bottom line, please don't rely on fantasies like I²S improving audio performance. Insist on measurements being provided to demonstrate audible change in the output of the DAC -- the thing you hear. Don't accept hand gestures as evidence. And certainly not any appeal to a lay person's intuition as a replacement for proper data providing proof.

I will test I²S more in the future as I get other devices with it in there. For now, don't waste a penny even thinking about it, let alone using it.

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Arguably a data stream with an embedded clock (such as Manchester encoding) would in theory be more foolproof.

However everything depends on implementation regardless of the digital transport mechanism.

I²S was originally intended for on-the-PCB digital transport over PCB traces with carefully designed impedances to avoid pulse relections. Using it through a cable seems a dicey proposition at best.
 
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