I2S sound: What to expect?

I’m three weeks into burning in an Oppomod HDMI to I2S internal card for an Oppo 203 and have a question about the sound of I2S. It comes from not knowing what to expect, as I’ve only heard I2S via the Oppo to a DS dac, mainly using PS Audio’s old I2S-12 (silver) HDMI, along with a little of the current I2S cable that comes with the DMP.

Specifically, with the Oppomod card, as well as the outboard card off eBay some of us got before it, when I switch from spdif via a good mid-level Snake River Boomslang to I2S there is a little rise in pitch and a dose of atmosphere added, something like a touch of processing or recording room acoustics. Together, they make the highs sound very extended, but also make instruments and the overall sense of the music more ephemeral, more floating in space, i.e., less palpable or solid and planted. With decent recordings, these characteristics are enchanting and help make for great dynamics (and listening from another room). But they also seem more artificial than natural, as if the transfer has added to the recording. I took Ted’s suggestion on another thread to unplug/replug all the power cords for the first time in many months and that definitely improved coherency top to bottom, but it did not change the atmospherics and pitch change. Between the three components involved – Oppomod card, HDMI cable and the DS – I’m not sure what to make of it.

I tried a CD with low frequency tones and the differences between spdif and I2S were obvious: with the coax, low tones such as 60 Hz sounded as they should, but with I2S there were strong overtones that made each tone seem like it came from a much higher frequency.

I’ve been thinking of experimenting with other cables, but before that it seems worth asking for others’ thoughts or suggestions, especially those that have used I2S with the DS. Thanks,

Run the bit perfect test - if the pitch is really different between two DS inputs then the odds are quite high that some sort of protocol violation or sample rate conversion is going on in one of them and the differences you hear are mostly from the unknown errors or the unknown processing.

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I went from a USB streamer to an I2S streamer and experienced the same phenomenon. The USB cable I was using was a Curious Cable and the streamer was an Ultra Rendu. I went from this combination which excluding power supply came in at about $1200 AUD retail and swapped it for an Audiphonics I2S streamer and a reasonably QED HMDI cable. I think the whole setup came in at about $600 AUD.
The difference between the USB streamer and the I2S streamer (which was a fraction of the price of the Ultrarendu) was immediately noticeable to everyone who I demonstrated them to. I simply swapped between the 2 end points in Roon then the DSJ picked up the change and would switch inputs automatically so I don’t think there was any funny business going on. I did let them know I was changing something but gave them no idea what.
There is more air, atmospherics, timbral information, smoother and richer. I am of the opinion, based on having used all the inputs on my DSJ with quite good cables and sources, that the I2S input is the cream of the crop. I know Ted might not agree on that - and I hate to sound contrarian! But perhaps its a by-product of less processing in the source unit and less in the DSJ (Ted might not agree on that point). Perhaps I2S / HMDI cables are more jitter resistant?? All I can say is that the cheap Audiophonics unit saw off the UltraRendu is smart fashion and everyone I let hear the 2 in comparison heard the same thing.
And I don’t think it is adding anything or shifting pitch in my setup. I am sensitive to those sorts of things and I am not experiencing any fatigue, even with this extra detail and vitality which is my litmus test so see if a change is really an improvement or whether it is just “different”.

Ted, I was unaware of that test, thanks. The green check and 'bit perfect" shows on both versions.

bag, your post appeared just as I was writing. I made it a new thread precisely to hear the experience of non-Oppo users. So glad to hear I’m not alone on this. In addition to CD’s and the occasional DVD/Blu-ray, with music I listen primarily to flac wav, dsd and mp4 concert files off USB flash drives and an SSD plugged into the Oppo via a TotalDac1 USB cable/filter with a cheap B to A adapter. I would say the differences I perceive are typically greater with the USB files than CDs, but present on all.

The pitch difference I hear is typically subtle and repeatable, although not always apparent to my hearing. What confirmed to me something is going on was the bass tone test difference, which caught me by surprise. At the time, I was thinking I2S was not as coherent top to bottom and acoustic bass was not as clear and solid as with the Boomslang spdif, so I decided to run the test. The result got me to do the unplug/replug. After that, there was coherence top to bottom and a much stronger bass, but the tone test came out the same. Going back and forth during each tone level between spdif and I2S with the SoundDoctor CD, the difference was night and day, as I recall most obvious from roughly 50 Hz on up with ATC floorstanding actives (SCM19A).

The high end extension and the extra atmosphere between the two is readily apparent with instruments, such as piano. It’s not so much lateral placement that changes, but fore-aft; with the Boomslang, a very capable cable, I can picture where the instrument is in that dimension, whereas with I2S it often floats backward into pleasant nether space (although I was able to place Joe Henderson’s sax relative to the back wall on the old Chesky demo CD).

As I mentioned, if I put aside these ‘features,’ it is a great listen and the dynamics really come through on well recorded ensemble jazz and lively classical, for example. No fatigue normally. The high end does give a sense of open ended atmospheric space upwards, and that is murder on bright high ends (and my ears) with not so well recorded music and most mp3’s.

FWIW: I have heard this same effect through both of the i2S interfaces I have tried so far (the Oppomod board and the Chinese HDMI to I2S board).

Although, with the Oppomod board, this effect nearly goes away when you set the power to internal. When it is set to external power, that is when it sounds almost like you have inserted a stereo-wide control into your system.

I haven’t tried the bitperfect test on the Oppomod board yet, but I have tried it on the Chinese board, and it passed, even despite the fact that it also performs this stereo-wide effect as well.

Just a few thoughts here. Have you let the I2S mod’ board run in a bit. I know people will say that’s rubbish but it;'s worth giving it a bit of run to see if the “wide” effect changes. It has been my experience that this often happens with new digital gear - the midrange sounds a bit vacant and fills in over time.

My recollection from one of the Oppo specific threads is that Ted said using the I2S card’s internal power nullifies the benefit of the dac’s I2S. Perhaps he can explain that some more.

bag, yes it’s been running in since Oct 15. Typically, 36 hours on (Oppo only), 8-12 hours off. I’ve heard substantial changes during that time (in addition to those from replacing Herbie’s big floor sliders with SVS isolators, which provided more insulation from the carpeted floor and its foundation and, at the time, a little less “aliveness”). The Oppomod card was “hot” straight out of the box. Very dynamic. Especially needed to wait for the high end and the atmospheric effect to settle down.

Your recollection is correct. This is why I decided to try the Oppomod card in the first place. However there is something strange which happens to the sound when using this board.

On some material I really enjoy this effect. But on other material, it seems to suppress some of the midrange from the sound. But the effect is not altogether natural IMO.

I’ve been switching back and forth with the power internal and the power set to external. And when the power is set back to internal, the part of midrange comes back, and when it is on external, it seems to almost vanish.

You might try unplug/replug of all the power cords, including the wall and any conditioners. Before doing that I was wondering if there was something missing especially in the 100-300 Hz range, but afterwards I found things had filled in. I had heard of doing that before, but was reminded by Ted’s comments in the “AC Power cable for the DirectStream - recommendations?” thread. Ted gave some interesting thoughts there about power cords, listening and audiophile superstitions.

I’ve powered down everything multiple times. But the effect remains. Frankly the effect sounds wonderful on most Rock, and really helps to lend more of a 3-D effect to the sound. But it sounds distinctly less wonderful on some Jazz and especially on classical IMO.

I hear this same effect with the Chinese adapter, but to a lesser degree. I have a unique configuration in that I can switch between the Oppomod card, my Vanity HD and the Chinese Is2 adapter at the press of an input button on my DS.

I can tell you without a doubt that the Vanity board does not have this effect at all, and that the Chinese adapter has this effect to a lesser extent than does the Oppomod board, when the power is set to external. But when the power is set to internal, the Oppomod board gets its focus back, and the nearly missing portion of the midrange spectrum returns.

The other thing that I notice is that the Oppomod board sounds brighter than either the Vanity HD card or the Chinese I2S adapter regardless of whether the power is set to internal or external. Its almost like a treble control has been turned-up slightly. So I completely understand why you have been searching for warm I2s cables, because this thing just sounds a bit on the bright side.

I’m going to try the bitperfect test on this card shortly just to verify that this is not some kind of processing inside of the oppomod board.

Ok, I just tried the bitperfect test both ways on the Oppomod board, and it passed both times!

So, unless there is a way to fool teds bitperfect test, signal processing is not the explanation for this anomaly.

By power down, I assume you mean actually unplug all cords. For me, this is an I2S specific issue, so the Vanity card is out on that unless you wired in the little I2S card someone on that forum suggested. I’ve been feeling the need for a warm HDMI much less the past couple of days. It’s much closer to what I want and I don’t find a significant brightness that bothers me as much as the Vanity card did. I found the latter tonally elevated across the board, so that pianos almost sounded like player pianos. With the Oppomod, there’s a point of whether to play with HDMI cables, which requires some going blind because they are hard to get to audition. Plus, I’m not sure there is such a thing as a warm HDMI, since most are designed to be dual purpose. If I can’t get some good guidance, I may live with what I have, which is very good, and get a better spdif one.

Oh heck. This is getting interesting :wink:

Yes, I physically unplugged them, and did not simply put these into standby.

And yes my vanity card is definitely functioning properly. I merely needed to acquire the proper 22 pin cable to finally be able use the “pass through” feature on the Oppomod board so that I could run my Vanity card again.

I’ve played around with a handful of cheap HDMI cables so far (including one which was highly recommended in one thread), and they do change the sound a bit. But ALL of them sound brighter though the Oppomod board than they do through the Chinese board, or by comparison to the Vanity HD’s output.

I’d love to try some better HDMI cables. But I’m extremely skeptical that a big-buck HDMI cable is going to resolve all of these issues.

Run my DS and i2s Oppomod’d 203 into
a 300B SET amp with very good power tubes.

Synergy maybe, but it hits the spot for me.
Have a linear power supply as well as the Oppomod clock femto clock upgrade, any digital edge has been removed.
Fitting a Furutech silver wired IEC inlet, dampening the case and paying attention tomwhat the Oppo sits on makes a a nice imorovement too.

i2s is amazing into the DS, as an Oppo owner its worth pushing the boat out of what this amazing machine can do, especially with the DS.

Cant wait for the new DS firmware upgrade.


Well, I don’t know your taste, but if you’ve overcome the problem being discussed here, a digital edge not really being something I’d noticed, one has to guess that a tube amp might be an awfully important element.

Not implying I’ve ever had the issue to be clear, just offering some (hopefully) useful experience with what I’ve learned from someone with the similar kit, and how my tiime with it has went.

gazjam, Just so I understand, are you saying that the HDMI cable from the Oppomod card goes directly to your amp and not through the DS dac to the amp?

The hdmi cable from the Oppomod card goes directly into the Directstream i2s input.

Hi scumbag,

I’ve just ordered an Audiophonics Rapsdigi as yours to connect into my i2s input in my DS jr. last week i’ve purchased a CDT-8 and this i2s input is a revelation!

My question is… Is difficult to set up? It’s just plug and play or do I need to configure or install some software?

Thanks in advance for your answer!

José Luis from Spain.