Problems using I2S

Roon Core: MacMini (i7 late 2012) running Roon 1.7 Build 511
Network: Ethernet (incl. some fibre converters for EM noise reduction). Central switch in house = TP Link Archer D7
Endpoint: SMS 200 Ultra neo with clocked switch
Output: Curious USB > Intona USB filter > Matrix Audio X SDPIF > Coax > Topping D70 dac.

Hi there, I’m trying to solve this issue with I2s from the Matrix to D70.
While the Coax is fully operational, the option that I’m trying to get working is the I2S from the X-SPDIF to D70. This has worked once or twice on boot-up bu tis very unstable. I’ve looked at and checked over the dip switches on the Matrix, and the internal settings on the D70 several times.

I know the Matrix outputs I2S to the D70, since when I feed the Matrix XSPDIF USB from laptop the I2S works just fine.

Option 1 - The SMS 200 is the issue, which is quite possible although there are very options for altering the settings.

Option 2 - Roon settings. The reason why I think that is a possibility is that when I try to use the I2S path on the dac Roon often behaves very strangely and skips through and tries to play about 10 tracks and then stalls. and loses the SMS. This may be SMS, or Roon, and I can’t tell.

I did read on the Roon Community from several years ago that it wouldn’t work with PCM > 24 bits. I’ve tested the bit rate line of investigation, and it makes no difference.

Anyway, and suggestions for further investigations are very welcome, as I’ve run out of ideas for the moment.


Hi @Graeme_Newell,

Is the behavior the same if you try using another app to start audio playback (such as Foobar)?
Where exactly in the chain does the SMS 200 fit in? Could you try bypassing it to eliminate it as a variable?

Thanks for the suggestion Noris
The SMS is a Roon Endpoint on ethernet with the core in another room. I might try and temporarily bring the core closer and run it direct and see whether I get the same effect.

Also the Eunhasu OS on the SMS hosts other apps including Shairport, Bubble UPnP, LMS & SQueezelite, MPD & DLNA, Minimserver, HQPlayer NAA

I have used Shairprt once in the past to test it with an earlier OS implementation, but this current one seems to have trouble installing.

I’ll read up on some of these options and hopefully get one of them working to test it … good thinking !

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I finally got around to the next stage of sleuthing and here’s the results - hopefully this is useful to others.

In short, if I move the roon server (mac mini) next to my gear & connect to the local ethernet switch, I get the same response - i.e. the Matrix will output coax to the D70 dac, but not I2S.

However, if I use USB straight out the Mac Mini direct to the Matrix SPDIF, then both coax & I2s work well using Roon … So the problem resides in my SMS 200 Ultra renderer. !

And is it worth chasing I2S output rather than USB or coax for improved SQ ? Absolutely. Much improved soundstage depth, voice/instrument placement, transparency.

Very good, but I do need to find myself a much more compatible renderer, or go to a locally placed NUC / Roon Nucleus … unless there are other smart suggestions ??

Hello @Graeme_Newell,

Glad to hear you’re up and running via USB from the Mac to the Matrix SPDIF!

Unfortunately, we don’t have this device in-house so we can’t guarantee compatibility with Linux-based USB hosts such as the SMS-200.

As the next step, I would reach out to Matrix Audio to see if they can confirm Linux support.

Good Idea - I’ll follow that up, and also check in with some of the SoTM / SMS 200 forums and see what I can find


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