MQA over Coax Compatible DAC's?
Apr 4, 2021 at 4:31 PM Thread Starter Post #1 of 4

fjlabs

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I just got the Bluesound Node 2i and it can only output digital via Coax/TOSLink. Most MQA compatible DAC's are only able to do the three MQA unfolds through the USB input and just completely skip that functionality over Coax.

Are there any DAC's that are able to unfold MQA all three times over coax? Seems like the Gustard X16 is able to, but are there any other options out there?

I don't think it's too rare of an option, since the Node 2i even has a dedicated MQA bitperfect-over-coax option in the app.

Edit: Here's a rolling list of some I've found:

  • iFi Pro iDSD ($2,750)
  • iFi Neo iDSD ($700)
  • Gustard X16 ($500)
  • Mytek Liberty ($1,000)
  • Mytek Brooklyn DAC+ ($2,195)
  • Mytek Brooklyn Bridge [II] ($3,500)
 
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Apr 5, 2021 at 1:20 PM Post #2 of 4

gimmeheadroom

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Brooklyn DAC+ is apparently not being made anymore. The Liberty II looks to have some upgraded capabilities over the previous model but not sure it is real until they start shipping. You could ask Mytek if they will process MQA from the coax input.

Matrix has some DAC with coaxial input. Doubtless there are high end boxes that also do.
 
Apr 5, 2021 at 1:39 PM Post #3 of 4

Roseval

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Are there any DAC's that are able to unfold MQA all three times over coax?
Probably not.
There are all kind of audio formats, lossless ones like WAV, FLAC, ALAC , etc and lossy ones like MP3, AAC, MQA, etc.
What they do have in common is that no DAC understand this type of formats.
Hence a media player convert these formats to a protocol a DAC understand.
This is raw PCM audio over SPDIF, AES/EBU, USB, etc.

In case of MQA, the software might do the second unfolding, use the info stored below bit 17 to re-created the frequencies above 44/48 and upsample in the process to 88 or 96.
The last unfolding is only allowed in hardware, a DAC with a MQA license can recognize the watermark and will apply the MQA prescribe minimum phase filters and up-sample if needed.
If you have a device with digital out, it won’t do the 3thd unfolding on this port because this is not allowed by the MQA license policy.
If it can send the bits unaltered (the water mark is somewhere in bit 1-16), any MQA enable DAC can do the last unfolding.
If your DAC already use minimum phase filtering and up-sampling (almost all DAC up/oversample) you might wonder if you really need this last stage to reproduce this lossy format properly.
 
Apr 5, 2021 at 4:03 PM Post #4 of 4

fjlabs

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If you have a device with digital out, it won’t do the 3thd unfolding on this port because this is not allowed by the MQA license policy.
If it can send the bits unaltered (the water mark is somewhere in bit 1-16), any MQA enable DAC can do the last unfolding.
Yep, I'm aware that I can't output "unfolded" MQA via digital because of the licensing restrictions. However, my Bluesound Node 2i is able to bit-perfect MQA streams over S/PDIF.

Most MQA DAC's are able to take bit-perfect MQA PCM FLAC's over USB. If the DAC is MQA licensed (i.e., Khadas Tone 2 Pro, Topping D90 MQA, etc...) it should be able to unfold all 3 times (full MQA Decoder + Renderer) and that's been my experience with MQA DAC's over USB.

Unfortunately, the Khadas Tone 2 Pro (that I have) can't do the same with an MQA stream over Coax S/PDIF. From my research, it seems that some DAC's are able to process MQA (full Decoder + Renderer) via S/PDIF so I'm trying to compile a list of possible options.
 

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