Sample rate changes 2-3 times (ticks on DAC)

Continuing the discussion from Sample rate changes 3 times:

Roon Core Machine

Mac Mini 2018 i5 32GB as Roon Core (actual version)
OS Ventura 13.1 (last, todays Mac OS update not installed yet)

Networking Gear & Setup Details

Connected Audio Devices

Stello U3 connected to USB, XMOS USB 2.0 Audio Out used
Stello is connected by SPDIF output to Proceed PDP3 DAC

Number of Tracks in Library

Description of Issue

I have the same issue as described in the linked old post.

At the start of the playback or if the frequency / resolution of track changes then 2-3 ticks occurs on DAC (relay), normally it would be just one.

It looks like Roon was “fighting” with Mac OS about the Stello U3 device and Roon afte 2-3 tries win :(.
Sound effects on Mac Mini OS are set to speakers, not to Stello U3.
I tried almost every possible audio setting in the Roon.
So last chance seems to be to change smth on Mac OS side.

Any ideas please?

Thank you very much. Best regards,


I would also like to add the following information:
When I connected the Stillo U3 + Proceed PDP3 DAC via Roon Windows application (endpoint), WASAPI driver, the repeated switching on the converter does not happen, the relay sounds only once, of course, only when the resolution changes. So this will be caused by either the Roon application for Mac OS or the XMOS USB 2.0 Audio driver that Mac OS used for the Stillo U3 USB-SPDIF converter. The question is whether it is solvable configurationally or does it require SW modification and then the question is whether it is on the side of the Roon Mac OS application or it is a matter of the XMOS USB 2.0 Audio driver.

One more information, it only happens when I set Exclusive mode. If it is turned off, it does not do this, which is logical, since in that case the resolution is unchanged regardless of the resolution of the track being played.

I will be grateful for any tips. I have already exhausted all the possibilities that have occurred to me so far.

Thank you very much, Richard

Hi @Richard_Kufcak,

Are you able to supply a screenshot of the Device Setup page in Roon → Settings → Audio for the Stella USB DAC when connected via the XMOS driver?

Additionally, a screenshot from your Mac OS Audio Midi setup app for the Stello/XMOS will be helpful (Applications → Utility → Audio Midi Setup). See below for an example:

Keep in mind that RAATServer will also await confirmation from the DAC firmware that the anticipated sample rate has changed to match the new source content before emitting the audio stream. As a test, try setting a maximum sample rate in Device Setup, as well as a maximum resync delay, and then adjusting from there.

Is other software on the Mac using the XMOS drivers (LogicPro, etc.).

Thank you for the answer, sorry, but too late. I meantime tried several other options. For now I decided on a dedicated fanless PC with LPS+Windows+JPLAY+Fidelizer and Roon Bridge which change the sample rate correctly and SQ is uncomparable as directly from Mac Mini, my Core Roon server.

Best regards, Richard