Sorry, which CD transort do you use and has this functionality. I am curious. And agree, if would be nice, if RME would incorporate this feature.

Does this make sense at all, I2S is rather exotic. Whether you transfer lossless over one or the other type of digital transport makes no difference in sound or quality. It's digital, it’s lossless, what do you want more?

I could imagine that devices that have an I2S bus certainly also support other more established interfaces.

I2S would in my opinion, only unnecessarily increase the cost of the devices and make the routing even more extensive / complex.

What I am also missing is a motivation or perspective, why one should do this at all. What will really be better as a result?

I²S is intended for internal communication between chips within a single device.

I‘m not even sure a true standard interface (connector, signal levels, cable impedance etc.) for outside connection exists.
Mis-using a special wired HDMI-cable seems to have become more common, but that’s more a convention than a true standard, and pinout varies between manufacturers.

I don‘t see a practical technical advantage of I²S over the established AES / SPDIF / ADAT / MADI digital audio formats.
In contrary, the separate clock lines makes I²S prone to all kinds of errors with distant interfacing.

It's true that I2S is not a standard in HiFi.
However, the HDMI connector is the one that is usually supported along with a standard HDMI cable.
Companies like Denafrips and others support typically 8 different pin configurations that you can toggle through.

Unlike S/PDIF, for example, audio data and clock information are transmitted separately at the I2S output. A separate line is available for the master clock. This eliminates the coding/decoding effort and the reconstruction of the sampling frequency, which could result in lower jitter.

The HDMI connector and cables provide excellent electrical properties for the I2S connection. The HDMI interface for the 4k/8k video transmission are the best proof of that.

For the "practical advantage" see my initial post.

Again, as written in post #1: My transport does not provide an USB interface!
Maybe I2S is not for Pro audio but for HiFi it is getting more and more popular.
I guess having the choice to use the interface that is best suited for a specific use case is a good thing.
RME needs to decide in which market they want to play or eventually provide a dedicated ADI-2 Pro HiFi version in a larger chassis.

There are many good examples in the industry where existing interface technologies were later on adapted for new applications. Best example is Ethernet which was further enhanced and will be the key networking technology for enabling autonomous driving.
Following your very conservative path then there would be hardly any innovation and we would still rely on the CAN bus with 1 Mbit/s….

Can you please elaborate and provide some evidence on why you believe it's "not performant"?

Hi Kai,

thanks for the interesting link!
Let assume I would connect the I2S output of my transport with this board playing music at PCM384.
Does this board then automatically downsample e. g. PCM384 to output PCM192 at the SPDIF output?
How is then DSD handled?

I guess this could also be used to directly connect it with the Raspberry Pi to add a SPIDIF output.

Yes that should work but would still limit the I2S output to 192kHz.
The perfect device would be a digital to digital converter (DDC). Unfortunately the DDCs I found do only provide an USB input but no I2S input.

https://magnahifi.com/de/singxer-su-2-u … -i2s-hdmi/

Can't quite imagine why the market is not full of these.

Edit: Oooops, it is. I own one of these https://magnahifi.com/de/matrix-audio-x … interface/ to connect USB to AES/EBU. Did not realize it supports I2S, nor do i care.

Have you seen (Video at 12:08) he has PLL Off for making a tiny sideband difference between SPDIF -139 dB, and I²S -142 dB visual?

For the ADi-2 with it‘s highly developed internal re-clocking jitter is of no concern anyway.

The most important statement in the video is at 8 minutes, where he says:
“The jitter removal devices only makes sense if it’s clock is better than the one built into the DAC”.
This is usually not the case with ADI-2!

Or at 4:20 in the video
“This video is not about what’s audible, what’s not, what makes a difference”
I am glad RME is not spending valuable engineering hours chasing after the audiophile market.

You mean catering to the audiophool market that you falsely claim to be the HiFi market? Personally I'm quite happy with the RME devices I own, and yes, it's High-Fidelity.

This is a general observation and is not specific to I2S.

Okay, so let‘s ask ChatGPT as a neutral source about I2S and it‘s relevance in HiFi.

Is the I2S interface relevant for the HiFi industry?
Yes, the I2S interface is very relevant for the HiFi industry. The I2S interface, which stands for Inter-IC Sound interface, is a serial bus interface standard used for transferring digital audio data between integrated circuits in electronic devices. It is commonly used in digital audio applications such as digital-to-analog converters (DACs), amplifiers, and other audio processing devices.

In the HiFi industry, the I2S interface is widely used for high-quality audio applications because it provides a high-speed, low-jitter digital interface that is capable of transmitting high-resolution audio data with minimal distortion. This makes it ideal for use in audiophile-grade equipment such as digital music players, high-end amplifiers, and DACs.

Furthermore, many high-end DACs feature I2S input ports, allowing them to receive digital audio signals directly from sources such as CD transports or digital audio workstations (DAWs). This can result in improved sound quality compared to other digital audio interfaces, such as S/PDIF or USB.

In summary, the I2S interface is a crucial component of high-quality digital audio systems and is widely used in the HiFi industry.

ChatGPT is not always accurate and does not tell you if the results are based on facts or if ChatGPT interpolates information and thus comes up with incorrect results. So, you better be careful and not too AI-believing. It is also bad style to use AI as a killer argument. Better think a bit yourself if I2S is of any use at all in the typical application scenarios for ADI-2 DAC/Pro.

For example, when I bought my Accuphase Class A amplifier a few years ago, it was neither relevant nor hip to look for products with I2S interfaces. HiFi also always uses the "traditional" digital interfaces like S/PDIF and HDMI, which also work lossless. As far as ADAT and S/PDIF are concerned, RME already has a unique selling point with SteadyClock FS, which perfectly eliminates jitter.

In typical use cases for the ADI-2 DAC and Pro, digital audio files are transferred to the device lossless. The "Bit test" feature allows you to validate lossless transfer using small .wav files that you can download from RME for free. SteadyClock FS effectively eliminates any clock jitter. Even at the highest jitter values that can only be artificially generated in a lab (and are not surpassed in practice by the worst playback devices), SteadyClock eliminates jitter entirely and reliably. These now completely jitter-free digital audio signals are converted using the device's own FS clock D/A converter, thanks to the special design of the ADI-2 DAC/Pro. This means that the ADI-2 functions as a "clock slave" and performs D/A conversion in the best quality, completely independent of the clock quality of the clock master.

Furthermore, with the ADI-2 DAC/Pro, you have other device-specific advantages such as different reference levels (4, and even 5 on the 2/4 Pro SE) and automatic switching of reference levels to ensure that dynamic range/SNR remain high over a wider range. Even settings for B/T, PEQ, and dynamic loudness are considered, and the optimal reference level is always chosen.

All of these advantages are available to you when you simply connect the ADI-2 DAC/Pro in the traditional way. There is no need for I2S, nor do you need to purchase a new device to get I2S. I really think I2S only came up in HiFi industry because they had nothing comparable to SteadyClock(tm). But now you have an RME device with proven studio technology and SteadyClock FS. This is a game changer, simply use it wisely in your setup and then enjoy.

I believe that in the end, these advantages provide more benefits than considering the implementation of an I2S interface on the ADI-2 DAC/Pro, which would unnecessarily complicate and increase the cost of the device.

Take a look at this video to get information about SteadyClock technology: https://www.youtube.com/watch?v=Ti0aHW-zYcs

In my audio chain I connect other devices like TV, BluRay Player and Recording interface through ADAT and S/PDIF. Many other people also do so.
Then the ADI-2 Pro is the central instance performing the D/A conversion which makes sense according to the special features of the product.
The rest is analog audio transfer to HiFi Pre or Power Amp or integrated amplifier like in my case Accu E-600.

Again, I see no demand for I2S as most people are using products like ADI-2 DAC/Pro in such a way (getting digital audio data either from USB, ADAT/SPDIF or AES). And then for the final D/A conversion in highest quality using the internal FS clock.

In my case, the signal flow is this:

PC--Audio Player---UFX+---ADAT1--------------------------------+-------ADI-2 Pro FS R BE----Analog----Geithain RL906D
                                \                                                                                               \----Analog----Audeze LCD-3
                                 \
                                  +----ADAT2---------------+ Optosel 4:1 +------ADI-2 Pro FS R BE---Analog---Accu E-600---Speaker
                                          BluRay/SPDIF-----+
                                          TV/SPDIF-----------+

I don't like to submit to the dictates of the industry anyway, always throwing something new on the market, which ultimately brings no advantages (at least not for somebody having an ADI-2 DAC/Pro). Rather the disadvantage that you have to spend money again for no real reason.

It's best to set up your setup intelligently enough to escape this dictate. These are still areas where we are ahead of an AI and that's a good thing.

To sum up. Audio transmission in the setup described above is lossless and the ADI-2 Pro performs a very efficient jitter suppression by SteadyClock FS and performs the final D/A conversion with its internal FS clock. With I2S it wouldn't get any better than this and I2S wouldn't provide any advantage in terms of lossless transmission or jitter suppression.

Hey, I just solved the problem, asking ChatGPT:

Question:
“Does ADI-2 Pro support I2S?”

ChatGPT:
“Yes, the RME ADI-2 Pro does support I2S. It has an I2S input and output, as well as other digital audio inputs and outputs.”

Who am I to question that?

So @Pervasive_Silicon, do your I2S connection and enjoy the music.

- Case closed -

+1

Guys,
Thanks for all your feedback!
I think the list of vendors (except RME) that ChatGPT has put together is pretty good. Of course there are many more vendors out there that support I2S.
As stated in my initial post, I just wanted to use the I2S interface of my streamer/CD transport to listen to SACDs because Sony and Co did only allow the HiFi industry to output the DSD signal via HDMI but not via SPDIF or AES.
I‘m first and foremost a music lover and EE engineer but certainly not somebody who spends a fortune in cables and other nonsense.
I also use my ADI-2 pro to perform some audio measurements on my HiFi gear - just for fun.
Since I use the ADI for room/headphone correction all my HiFi sources are routed through the ADI.

Even there are better sounding DACs (with I2S) out there they cannot offer me such a great feature set.
Since functionality is more important for me than sound quality I‘m clearly not an audiophile :-)

PS: For an I2S connection you can use any cheap HDMI cable <= 1.5m for 10€!

In this case the mentioned I2S to SPDIF converter is the solution.
https://forum.rme-audio.de/viewtopic.ph … 55#p200855
As copy protection can not be transferred through I2S it works like a filter for it.

On disc you anyway only find, to my knowledge, DSD64, so SPDIF’s 192 kHz sample rate limit is of no concern either.