MQA Core Decoder getting engaged, even for native "Decoder and Renderer" device

I noticed that the magic MQA light wasn’t coming on on the Meridian Prime when playing an MQA-encoded track.

That zone is configured as “Decoder and Renderer”:


(and while checking this out, I tried both settings of the “Enable MQA Core Decoder” toggle with no change in this observed behavior)

Looking at the Signal Path trace, I see that the MQA Core Decoder is getting fired up. I assume that this is what’s breaking the stream from the perspective of the Prime.

Note that this is happening while this zone is part of a synchronized group, and RoonServer is v1.5 build 339.

When I took this zone out of the synchronization group and played directly to it alone – hardware MQA decoding worked again. We see that in that case, there’s no MQA Core Decoder step in the chain:


Now… note that one thing included in build 339 was a fix for the problem of synchronized groups containing one native MQA device just blowing up and stopping play if they started to get fed some MQA content. And build 339 did indeed fix that problem.

If the behavior I’m seeing here is an artifact of a workaround which avoids that earlier problem… note that this current behavior is far less disruptive than the breaking-and-stopping-play bug. If I had to choose, I would happily live with no MQA decoding for my single native MQA device only when it’s in a synchronization group rather than risk going back to the sudden-failure syndrome of yore… but I’m mentioning this current behavior in case it’s unknown.

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Thanks for reaching out, @Jeffrey_Moore!

In the latest release we made a change here which is causing the behavior you’re seeing. When using grouped playback, if any of the devices in the group require MQA Core Decoder we send the MQA Core Decoded stream to all devices, regardless of MQA capabilities.

The Meridian prime is a special case where it’s unable to operate in MQA Renderer mode — i.e. it only works when a non-Core-Decoded stream is sent and it acts as an MQA Full Decoder.

This is expected behavior here, and when not played as a part of a group where Core Decoding is required you should see the MQA capabilities of the DAC be utilized.

I hope this clears things up!



I realize the Prime is now oldish and has become an MQA edge case. I can live with this compromise, your devs should be free to focus on parts of the code with more general applicability. I just wanted to make sure you all knew this was going on.

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