My experience so far with NAD C658 and Roon

Hi, if I use the volume leveling or Headroom management when playing MQA then I will loose the MQA logo on the front display of the C658.

I have set the C658 for MQA capabilities to: Decoder and renderer (Full MQA DAC)
Advance settings I disabled : Roon MQA core decoder (Off)

No matter what I use in the advance settings for Roon MQA core decoder (enable or disabled)
I always loose the MQA logo on the front panel of the C658 if I use volume leveling or headroom management.

Does this mean the MQA full unfold is altered and I really need to get this logo to have full MQA unfold ?

Other finding

The speed processing is way faster if I set the MQA capabilities to: Decoder and Renderer and disable Roon core decoder. I don’t see any speed so it’s more than 100x for a MQA of 352.8

When I set the MQA capabilities to: Renderer only and use Roon core Decoder the signal path show a processing speed of 30x with MQA 352.8 and with this settings I loose the MQA logo on the front panel. In the signal path I have the ORFS to 352.8 in the signal path.

So to keep the MQA Logo on the front panel I need to put these settings
MQA capabilities: Decoder and renderer
ROON MQA Core Decoder : OFF
No volume levelling
No headroom management

Dirac Live

Problem with Dirac Live filter (enable) and FLAC audio files at 24/88.2

If the Dirac Live filter is enable and start a FLAC with 24/88.2 sampling rate I will have an error: “Roon Lost control of the audio device”

If I disable Dirac Live filter prior to start the FLAC at 24/88.2 it will play start correctly and after I can enable “Dirac Filter” but I will get a big boost in sound level for FLAC of 24/88.2 (only)

I don’t get the boost level with MQA at 24/88.2 or other sampling rate.
Same for FLAC files rate (16/44, 24/44, 24/48, 24/96, 24/192)

ONLY FLAC at 24/88.2 is the problem with Dirac Live enable

So I cannot activate Dirac Live filter when playing audio files with different sampling rate (FLAC or MQA) because when a FLAC at 24/88.2 start it will stop playing on the NAD C658 (Roon lost control of the audio device)

This bug is their for over a year and still not fix. Now Roon and NAD are certified so this should be resolved and fix.

Please make this work with 24/88.2 FLAC and fix the volume boost when using Dirac Live filter !

Already contact NAD about this issue with no solution.

Does this not mean the data has been altered and your not hearing the data as it was intended or recorded?

Would you not have Roon do the first unfold if you are using Roon DSP then the MQA signalling would be passed on the the renderer?

As soon I use in the advance settings the “Roon MQA Core Decoder” and MQA capabilities to Renderer and let Roon do the first unfold I loose the MQA Logo on the NAD C658 front panel display.
But in the signal path looks like the MQA signaling is there and should fully unfold.

But if I use these settings
MQA capabilities : Decoder and renderer
Advanced settings: Roon MQA Core Decoder enable

It will work and keep the MQA logo because since I don’t use any DSP or volume leveling it will bypass the Roon Core Decoder and use the internal MQA DAC but as soon I use volume leveling I will loose the MQA Logo and get this in the signal path

But the MQA logo on the front panel is gone.

Maybe it’s just a bug for MQA Logo on the front panel display ?

This is your mistake. You need this set to on. Roon will perform the first unfold, save the MQA rendering info, perform the processing you want, and then restore the MQA rendering info before finally delivering to the endpoint.

With the endpoint configured as both decoder and renderer set, Roon will send the raw MQA when it can, and then when you have anything that requires additional processing, it will do as described above.

With the software MQA decoder disabled, you must deliver a bit-perfect signal to the endpoint to get MQA decoding, and that means no additional processing as you have discovered.

There is no SQ benefit in forcing the endpoint to do the MQA first unfold.

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I was just wondering why I loose the MQA logo on the front display as soon I use volume leveling. Maybe it’s just a bug in the firmware.

I’m curious to have feedback from other people if they have the problem with Dirac Live filter and FLAC at 24/88.2


The same is happening on Arcam SA30, which I wrote about in the following thread: No MQA on Arcam SA30 (Roon Ready uncertified)

Arcam also supports Dirac, so just for the record, here I don’t have similar problems. The difference between NAD and Arcam is that NAD is certified and Arcam not (yet?).

This path looks ok for me. Remember that MQA is not compatible for DSP per se. Roon could do a lot (with its own DSP engine) but lossy MQA is closed for external digital processing. That is part of this format so you are limited to do smth more with signal.

I’m having the same issue. Did anyone ever figure this out?

To get the MQA logo on the front display you need to disable any volume leveling or DSP

  • Volume leveling (off)
  • Headroom management (off)