Sonore Opticalrendu + Ultradigital: does it make sense?

Hi, does somebody have experience with using of Sonore Ultradigital for i2s output in combination with Sonore opticalrendu?
I read much that i2s sounds better than usb of a dac?
I now use opticalrendu with usb to the dac.
My dac also has i2s. Would it bring a sq boost if connecting Ultradigital between the opticalrendu and the dac to use i2s?
If somebody has experimented with this combination I would be happy to read your experiences. Thanks!

It totally depends on the DAC. My Holo May KTE sounds at least as good from USB as it does from I2S, and its fast USB allows me to use SDM to DSD256 to achieve my favored sound profile (I could go to DSD1024 but I don’t need to and it would cost me more on the HQPplayer server side). The Metrum Onyx and Holo Spring 1 DACs I owned in the past did better with I2S. DACs with well-designed and implemented USB receivers can do better because they buffer and clock the digital signal to meet the DAC’s needs. With I2S, there’s no buffering and the clock is given by the I2S source, so you have to be sure the source is high quality, including the cable.

Thank you for the informative explanation!
My dac is smsl vmv d2. Has xmos xu216. Don’t know how goog the usb section is in this dac.

The relative quality of different DAC inputs regarding jitter or electrical noise leakage cannot be determined from component specifications, it is much more a matter of design and implementation details that can only be revealed by testing. The good news however is that differences between different inputs in current DACs from good brands tend to be small. I’ve used USB>I2S converters in the past (from Singxer, the Ultradigital did not exist then) but that was for older DACs with suboptimal USB inputs.

See 13th Audiophile review, Holo Audio Spring 3 DAC Level 2 (vs. Denafrips) feat. Sonore opticalRendu/ultraDigital - YouTube. Ultradigital into I2s makes a (very small)
improvement, when talking about Holo Spring dac’s. In the case of Denafrip’s dacs ( my experience and other’s reviews) 12s is a clear improvement, through a Denafrips DDC.

One confounding factor in these comparisons is that good USB>I2S converters also provide signal isolation, so a more rigorous comparison might use an isolator (like the Intona isolators I use) in the USB path. That is, maybe the small benefit is added isolation, not I2S. Incidentally, Holo Spring 3 and May have an aggressive PLL circuit in I2S to counter source clock variability, which some people turn off to avoid long phase lock delays, but then lose the full benefit of the DACs own precise clocks. Which is another reason to use USB with those DACs.

Agree with you. Therefore was my original question about whether i2s by its nature something better than usb.
Thank your feedback guys I understood that to answer my question I have to try i2s of my dac.
In my dacs manual is written i2s can accept lowest jitter audio. Whatever it means, I would try it.
So I just ordered sonore Ultradigital.
Will report my findings if get it.

i2s can obviously sound better if the timing of the sender is better than in the DAC, provided you can tell the DAC to use the embedded timing in the signal. But i2s is also a lot easier to handle (USB needs its own little computer on the receiving end, i.e. XMOS chips), and the less “work” the DAC does the less internal noise will be generated.

My next streaming/DAC solution will use i2s, preferably without USB even being supported by the DAC. Not sure if such DAC exists though.

Contra this, I2S was designed for internal short-range communication within a DAC. Taking it external might have signal integrity consequences that were not contemplated in the protocol’s design.

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I would like to share my preliminary impressions about the change from usb to i2s input.
I just got the Sonore Ultradigital. It is a DDC. Usb to i2s.
It is still not burned in. So my impressions are actually just preliminary.
I used Sonore opticalrendu network players usb out into smsl vmv d2 dac.
Since opticalrendu is 100% galvanically isolated from the network jitter I thought that my current usb connection to the DAC is optimal.
Now I connected Ultradigital to opticalrendu per usb. And Ultradigital to the dac per i2s. Without to burn in the Ultradigital I experienced more analog, more engaging sound with bigger soundstage. The sound has much distortions as it is a not burned in unit. But if i imagine that the sound will become clean as with usb, it is definitely an improvement in the SQ.
I cannot explain that logically because what I did is the exchange of the usb input stage of the DAC through the usb input of Ultradigital.

An another interesting fact i do experiencing in the experiment. Through i2s the SQ difference between pcm and dsd stream (both upsample from pcm in roon) is very big. Although through USB it was almost impossible to hear the difference between pcm and dsd.
Through i2s dsd sounds much wider and deeper in the soundstage.

I will give an update of my further impressions after some days when the Ultradigital is burned in.