Grouped Playback and MQA

I recently acquired an MQA Dac (Mytek Liberty). I find in grouped playback MQA lock is fallible. There is no issue when playing to the Liberty by itself, but in a group when the Liberty is not the clock master, the MQA light occasionally switches from blue to orange, then back in a second or two. Sometimes there is more flickering than others.

Is this unavoidable when combining clock drift compensation with MQA? What would happen if two MQA Dacs are grouped?

I’m running the Liberty via USB with a Raspberry Pi 3B+ running DietPi 6.4 (upgrading now to 6.5) and 802.11ac. FWIW, the clock master is usually a Bel Canto RefLink.

Grouping destroys MQA integrity for now. I don’t know whether this behavior can be addressed or not.

If you’re doing clock drift compensation in the digital domain, and continuously–yes, it’s unavoidable. Some forms of drift compensation (for example, bending the clock rates in the analog domain) do not disturb MQA. Both approaches exist in the Roon Ready ecosystem, however with USB DACs, we are stuck doing things in the digital domain like you’ve observed.

With 2 MQA DACs grouped, the clock master would play bit-perfect and the second DAC would compensate like you’ve seen.

If you have just one MQA DAC, you might go into device setup and set its clock master priority to the highest position. This way, it will always run the show and compensation will happen on DACs that are less impacted.


Thanks for your insightful responses. I tried driving the Mytek Liberty over toslink via an RPi 3B and HifiBerry Dac+ Pro. I thought perhaps that setup would do clock-bending in the analog domain, but it appears to rate-lock the same as USB.

Out of curiosity, can you give an example of a Roon endpoint that does analog domain clock bending? Is this listed in some device specifications?


Bluesound/NAD products do. There are a couple others with custom output plugin implementations that I’m not sure about.

Most do not–either they lack the hardware components required to do it or aren’t up for the effort involved on the software side. This stuff is not very standardized on the software/firmware side, and can involve writing custom device drivers, or interfacing to custom hardware via very low level mechanisms. It’s also very time-consuming to test and validate.

I see. Thanks!

Roon 1.5 has addressed this problem for me. I now have Roon do the MQA decode step. I operate the Mytek Liberty Dac in MQA Renderer mode. This keeps the Dac from switching in and out of MQA mode when it is not the clock master. Problem solved!

Fun fact: The Mytek Liberty mode led is a light blue in render-only mode, rather than the deep blue of decode-render mode ;^).

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