MQA unfolding question

MQA is limtied to 24bit/96khz using anything other than a USB output. Since your DAC cannot recognize an MQA file at all the first unfold (in order to reach 24/96) will have to be done in software using Roon. Only an MQA capable DAC with a full decoder over USB can unfold files to 32bit/384khz. This is easier accomplished using a PC in the chain, but if you want to go thru a few hoops, it can be done with an Android or iOS phone. I don’t recommend the smart phone route because of the frequent updates to the operating system that can break compatibility. I actually have a DAC that worked with iOS 12, but now is gathering dust because of iOS 13. If anyone wants it let me know. You might have better luck with an Android phone.

This is incorrect. MQA Core (MQA decoded to 2x sample rate) can be passed to any DAC (with signalling information aka rendering metadata) over any digital protocol (USB, SPDIF, AES/EBU, Meridian MHR, Ethernet, etc.). MQA is never passed around in any form > 2x rates; in fact it is prohibited. The final unfold(s) take place in the DAC.

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I have a intresting question. I can play MQA files with my Head Box S2 Digital, it doesnt matter if I set it renderer or decoder Its plays them. Same thing with roon and audirvana. Does it mean that Head box is mqa dac?

You will always hear music as MQA is backward compatible by design. For the final render, you need and MQA DAC.

I actually don’t think we are disagreeing here. You can correct me if I’m wrong, but TOSLINK (SPIDF) has a real world limitation of passing audio at 24/96. And also a software unfold of MQA is also limited to 24/96. Only the second unfold unlocks the higher rates. My basic point was that to get the complete benefits of MQA there is only a USB solution available on the market.

I’m afraid that’s not correct. Say your MQA DAC accepts 96/24 on a coaxial SPDIF input. It can accept raw MQA, first-unfold MQA “Core”, and proceed to unfold/render it.

I understand it’s a digital file, but I don’t know of any DAC that actually works that way. DSD file no problem over SPIDF. But what actual DAC actually does the second unfold and authentication over TOSLINK? I would love to see a full MQA decoder that doesn’t have a USB input. That would really open up the market to more people being able to access MQA with full benefits timing and dejitter. Does MQA require two way communication? That’s the only reason I can think of for not using other digital inputs.

I wanted to add some more extra information because you had me thinking I was crazy. But these are the actual specs on my DAC (and I went online to check the specs on other DAC’s and they were similar). So here it is:

PCM over USB = up to 768kHz
PCM over Optical/Coaxial = 192kHZ

There is a hit to maximum resolution if you are not using USB. This is not atypical to my hardware.

Hi Hector,

High resolution non-MQA digital audio at 176k and higher sample rates needs a digital input at least as capable as the audio sample rate. As you quite rightly point out, typically only USB provides greater than 96k (non-network) input capability.

However, this does not apply to MQA which is transported to the DAC at either 44.1/48k (fully folded) or 88.2/96k (first unfold to “MQA Core”). A 96k digital input (TOSLINK, coax SPDIF, etc.) is therefore not a limitation when passing an MQA stream to a DAC.

The MQA stream that enters the DAC at max 96k is unfolded/processed inside the DAC. Depending on the hardware implementation in the DAC, the signal may be up-sampled to a sample rate higher than the 96k MQA transport sample rate. This secondary unfolding/processing is known as rendering.

Most do… TOSLINK and coax SPDIF.

No.


MQA sample rates are confusing. Perhaps this post of mine may help?

This Roon Knowledge Base article might also be useful: https://kb.roonlabs.com/Roon_x_MQA

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This is incorrect. My Lumin T2 performs both MQA steps (rendering to whatever resolution is intended) when fed the files via ethernet.

My Meridian 218/DSP 5200 SE does MQA on network too and I believe the spdif input suports MQA .
My Bluesound units unfold and render MQA via the Network. No USB audio here.

The original question was about SPIDF versus USB specifically. Also what you have would be considered a music streamer with a built in DAC not a stand alone DAC like the original question. But if the person wants to get a music streamer instead that might be a way to go.

Assuming their spec is correct:
https://www.hegel.com/products/integrated/h390
(Note: H590 is different.)

No. And it cannot do an internet license check.

You can connect MQA via TOSLINK. I mean that’s really the only way MQA-CD’s will work for the majority of CD players. It’s not a question of MQA playing nicely over a connection like that. The question is if you have separates. The Hegel has MQA built in so you don’t need anything but RCA outputs and call it a night. But if you an have outboard DAC and a music streamer with no DAC or MQA decoding you have a choice to make. Connect your music streamer via Optical or via USB. The better connection is USB. Granted this isn’t even a big deal. A majority of MQA files play below 192kHZ. For a very small substrate of files, mostly classical selections, you will get added benefit going over USB. I know some people are saying “MQA plays over Ethernet.” Everyone using Tidal or Qobuz is getting their music over Wi-Fi, Cellular, Ethernet. That’s a given. If you want to connect your music streamer (and everyone has one PC’s/smartphones are streamers). It’s USB you want to use. Maybe it will be USB-C in the near future. But it’s just plain old USB right now is what’s out there.

No, no, no! Any – any – MQA can be transferred to the DAC from a streamer or otherwise with a max 96k connection. That’s part of the point of MQA. High sample rates and USB are not required.

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You are not limited to 96k over USB. Why would you use SPIDF when both USB and SPIDF are both available? Why take a limit of 96k when you don’t have to? I don’t understand what you are saying. I say that SPIDF has a hard limit on resolution and you agree. You say “96k”. MQA files have the potential to render higher that. Granted over 90 percent of the MQA content is under 196k. You wouldn’t be missing much, but why miss out on anything at all? USB access is easily available. Remember the guys question was if he should use TOSLINK. Why would you unless you had no choice?

The first MQA unfold is a max of 96k so you don’t need higher capacity. Further rendering is done in the DAC.
This is as I understand it.

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Your not missing anything using mqa and optical or coaxial. This is something I don’t think your getting. You won’t get the benefit of hires from other sources past 96/24 for optical or 192/24 for coaxial but MQA the transport to the DAC is never higher than 96/24 regardless of what the master rate may be. The DAC itself handles the rest of the restoration/rendering to the higher up to 4x normally but this is dependant on the device. My Audioquest Dragonfly manage full MQA upto 384/24 yet it can only send upto 96/24 over the usb controller as it’s USB class 1. The same applies for an MQA DAC that accepts an optical or coaxial input for MQA rendering. Finding one that actually does this is the challenge I was saying. I don’t know one that does, but I am sure there are some out there.

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The Meridian 218 and the even more expensive 808v6 and 818v3 all render via coax and optical inputs. They are, of course, also Meridian Sooloos streamers, but I note that their streaming capability is only 96k, yet they are 100% MQA compatible.

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As an example, my Brooklyn Dac does the complete rendering of MQA flac files via Coax 192/24.

I believe the same is true of the popular (and very good) Pro-Ject Pre Box S2 Digital, but like the Brooklyn, that’s going to be a product feature choice rather than any actual restriction.