DAC issues with XMOS usb chipset and Roon on Linux

Completely agree - it’s why I won’t be buying any more Bluesound products and one reason I just sold my Node 2 :wink:

I am loving my Meridian Kit here. No mucking about or mods and tweaks required… Just great sound. :sunglasses:

Hi Peter,
Please note we are working on implementing the corrections to our XMOS firmware. It is worth noting that the same interfaces work perfectly with LMS on the same Linux platform. We have our music servers running Linux for many years working perfect. Sometimes we are forced to correct for many different things, some of which we did not cause. This is something new for us, we are working on a correction but unfortunately doesn’t happen overnight.

Thanks for the notice. I’m sure users of your XMOS based products will be pleased to know that you’re working on it.

By the way, I’m actually a user of another type of your product and am pleased with it :slight_smile:

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Glad to hear, thank you Peter!


Looks like I got the same issue with Mutec MC3+ USB on Linux… I posted it here Linux + Roon + Mutec MC3+ USB problem

How mature is the Mutec? Is the + version new?

I think it was released in 2016 so pretty new.

For those who believe that the Roon guys should add a patch/workaround inside the code as a quick fix, let me give you an argument that you will probably like.

Any quick fix/patch/workaround added to the Roon codebase will have an impact in the software development effort: debugging, testing, etc… All those things result in 2 things with a direct impact on your use of the software: more bugs due to the workarounds, delayed release of new Roon versions with all the features you are begging for.

So while fixing now in Roon sounds nice, also while it appears that the devs are taking the long road by talking and working with XMOS and the manufacturers using XMOS, this is the best solution, for them, and for you!

Sad but true…
I hope Mutec will step forward. I contacted them and they responded… I just had to clarfity what’s the issue.
Usually their CS is good.

Nice! Which company you represent @EJ_Sarmento ?

Wyred4Sound i believe.


Correct, thank you Simon.

It seems odd to me that Roon knows about this issue, but it’s buried in this support thread. It would have been extremely helpful for me to have seen a list of known good DAC’s, or at the very least a warning about XMOS based DAC’s. I’ve spent a lot of time troubleshooting this issue and working with Roon support who to-date hasn’t mentioned any of these details to me.

@brian I just read through this entire thread twice to be sure I didn’t miss anything important.

Here’s my takeaways:

  1. DAC’s with XMOS USB either need to be complaint to the USB 2.0 standard out of the box or if possible they need a firmware update to become compliant.
  2. Roon is alerting an unknown number of DAC manufacturers to their missing compliance to the USB 2.0 standard.
  3. There’s no listing of DAC’s that are compliant to the USB 2 0 standard.
  4. Roon could add a tenth of a second delay to the interface.

While I appreciate that the Roon Team wants to maintain their code base as it stands today, the premise that 100’s of DAC manufacturers will step up to the plate and update their firmware is aspirational at best. As the word spreads that ROCK, Linux implementations, and Nucleus don’t work with most USB DAC’s, Roon adoption of these implementations will slow to a crawl.

I spoke with a local Nucleus dealer about this issue today. They hadn’t heard about it. So now you have dealers selling Nucleus and DAC’s to unsuspecting customers. Sooner than later, the unsuspecting customer will experience the skipping issue. Now the dealer has to get involved. Eventually after spending time troubleshooting and opening a support ticket they’ll learn that the DAC that they have sold to the customer is “incompatible”. If I were that dealer I would immediately seize the sale of Nucleus. Why? There’s no list of what’s compatible and they might not be a dealer of compatible DAC’s.

Take this a step further. A customer with an existing DAC buys a Nucleus. The DAC isn’t compatible. The customer returns the Nucleus.

This position while admirable from a purist perspective doesn’t live in the real world.

I purchased all of the recommended i7 ROCK bits and pieces and a brand new Mytek Liberty. Why wasn’t a fully complaint DAC listing available to me? Why did I have to learn about this issue by the kindness of strangers? Why doesn’t the Roon Team respect my time and money?

How is it that none of the Audiophile reviewers are reporting this issue to their readers?

It’s CES this week. Lots of manufacturers are jumping on the Music server bandwagon. I personally am disappointed. I am 1/10 of a second away from being either a satisfied or ex-customer.

Why not apply the same rigor to the DAC manufacturers and dealers selling non compliant products? Just a thought.

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How many of these DACs with the XMOS/Linux issue are branded ‘Roon-Ready’ (and therefore I presume tested by Roon to get this status)? Does ‘Roon-Ready’ status test for this issue? I presume not and in any case it would only apply at the time of testing (as firmware can/will be updated and may break things).

Did PS Audio sort this for their DirectStream and DirectStream Junior DACs?

I fully agree with Vincent as I already wrote earlier in this thread.

I wrote to my DAC manufacturer who said he was not aware of any XMOS issue, I am still waiting/hoping for a patch on its side. In the meantime, ROCK is KO as an USB source for 2 monthes now… but the bill is paid: so far, I lost 20 USD + price of a RPi 3 as a temporary Roon end point.

I understand the purist approach in regards to DAC manufactures, but there is no warning sign on Roon web site except threads in Community. And again, my hardware was fine with various Linux distributions before Roon. The workaround for Roon should not be that huge and with no impact on SQ. In v1.6 maybe, but when?

That’s being said, the server is quite responsive and the app is really ´superb’!

Does anyone on this thread know of any endpoints that do not have this issue? I have a Sonore microRendu on my headphone setup and so far I haven’t experienced the skipping issue. Have I just been lucky?

What endpoints are you using with great success?