Explain degradation of kHz number

Can you explain why my MQA core decoder degrades the kHz from 352.8 to 88.2.

BTW, My NAD displays 176.4kHz.

“Degrade” is a poor choice of words. A software MQA decoder currently is limited to a first unfold, which is 1x or 2x the encoded sample rate. In this case, the first unfold is 44.1 kHz to 88.2 kHz. No degradation (other than the lossy encoding inherent to MQA). To achieve MQA specific upsampling to the 352.8 kHz original sample rate, a hardware MQA decoder is required.


I apologize for my use of words. I did not know any other way to explain it. My your answer, I assume that my NAD v3 does not have a hardware MQA decoder? If not, is there any way to achieve MQA specific upsampling to the original sample rate?

Your NAD is not involved in the MQA decoding process. Roon is the software MQA decoder.


As AJ says, the first unfold, called “decoding” by MQA, outputs an 88.2 or 96 kHz signal. The second unfold, called “rendering” by MQA outputs any increased original sample rate above that.

Roon is a software decoder. You will need a hardware MQA renderer to obtain the increased rates. Alternatively, you can upsample in Roon to the greater rate (subject to your DAC accepting it). This will accomplish some of the rendering process, but will not have the dynamic filters or 'time smear adjustments" that MQA describes.

And the 352.8 kHz original sample rate is just a number embedded in the metadata of the 44.1kHz stream, not data that the stream actually contains. Absent a hardware decoder, do not worry about it. Nothing is being downsampled.


How do I upsample in Roon?

When I play the same file through Roon and BluOS, I get different kHz display rates.

Both files are playing through Tidal.

I do not know all NAD model numbers, but that looks like an AVR, correct? How is it connected to the Roon core? Nearly all AVRs cannot ingest greater than 192 kHz. So, custom upsampling may be very limited in available sample rates.


It is the NAD 758 v3.It is connected wirelessly with a PC.

Are there any Roon settings that I can try to see upsampling works?

I still wonder why I get different kHz rates when I play the same Tidal file through Roon and BluOs (88.2 through Roon, 176.4 through BluOS).

To add more intrigue to mystery, when I play the same file through Oppo 203 the display rate is 44.1 kHz.

OPPO MQA decoding is exclusive to the UDP-205, not the UDP-203.


That explains the 44.1 kHz from the Oppo. What do you think explains the difference between Roon and BluOs?

Are there any Roon settings that I can try to see upsampling works?

Sample rate conversion in Roon is handled by the DSP Engine which is accessed by right clicking or long pressing the Zone Picker icon (symbol for the active Zone).

@steven_berne there seems to be some confusion here. The very first thing is to be able to interpret what you see when you see the details of a MQA encoded file. The original file is listed as TIDAL FLAC 44.1kHz 24 bit 2ch, MQA 352.8kHz. So your examples are as follows.

No MQA decoding, you get a FLAC file at 44.1, 24, 2ch

MQA first unfold in Roon you get 2 times that 44.1 rate hence 88kHz

MQA full decode but you get 176kHz, this is when your MQA decoder tops out at 192kHz maximum so it gives you the highest multiple of the original 44.1kHz it can deliver.

MQA full decode with a fully capable DAC will give you the originally stated maximum potential of 352.8kHz.

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Thanks Henry,
I haven’t seen that described before.

Thank you Henry (and everyone else). This answers my question.

Good explanation, I certainly didn’t know. To be fair, MQA hardly make it simple for consumers to understand.