David that was some effort there and thanks for taking the time to explain.
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Thats A great post Dave, Many Thanks.
I may have missed it but how does this relate to the MQA settings in Roon?
So if my Topping D70S MQA can do a full unfold whats the optimal setting for that DAC in Roon?
I’m guessing that’s why in a DAC like the Topping D70S you can only select one filter when using MQA?
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I get this question a lot. The best solution is usually to not lie to Roon about the capabilities of your zone. 
If it supports both decoding and rendering, say that. Leave Roon’s Core Decoder enabled. If you enable DSP, Core will decode and the DAC will render. When there is no DSP, the DAC will do both.
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Does it though? Here’s where the lossy / lossless confusion starts to poke out its ugly head. MQA “steals” 2 or more bits (I’ve lost track at this point) of the LPCM to “encode” the MQA stuff. Left alone, then yes, this is noise as the bits are not as recorded (encoded). The “unfolding” is supposed to restore these 2 bits and then move the MQA encoding up into the higher resolution part of the LPCM stream where the downstream DAC uses it to apply filters and whatever before restoring what it thinks the bits should have been (using something similar to an ADPCM process to reconstruct the LPCM).
It’s unclear to me how Roon is able to properly restore the high resolution part of the LPCM without the hardware assist (which is why it doesn’t). Maybe the first unfold is “good enough” for 88.2 (move the brickwall filter to double the resolution to reduce errors)? and the extra info the MQA DAC needs is up beyond the 88.2? In that way it doesn’t exactly “without MQA signaling” but simply has nowhere to put (we’re out of bandwidth at 88.2) to include the instruction set on what to do next. If that’s the case, what we end-up with is a couple bits of reconstructed 24-bit bitdepth, an upsampling operation to 88.2 (of unknown filters, although we can guess based on Bob’s thoughs on pre-ringing) resolution, and a LPCM bit-stream that should be the same LPCM bit-stream every time but is different than what was originally streamed / encoded.
Anywhooo… at the end of the day… If you’ve got a MQA DAC make sure its doing all the work for the most accurate bit stream. If you don’t have a MQA DAC at least let Roon reconstruct the missing couple bits.
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I never said that it did. AFAICT, Roon’s MQA Core Decoder implementation isn’t doing anything different than any other software solution, including Audirvana, the TIDAL desktop app, USB Audio Player PRO on Android, TIDAL Connect on licensed Volumio products, etc.
I don’t think it’s a question of properly restoring the high resolution part of LPCM. As you know, the first unfold in software always results in a 24-bit, 88.2 or 96 kHz stream, regardless of the original encoded sampling rate. If the downstream DAC does not support MQA, most software decoders won’t include MQA signaling in the lower order bits since that would just decode as noise in a DAC that can’t process it. Here, we’re discussing a difference in noise floor rather than bandwidth.
I take some issue with this statement. If the DAC does both decoding and rendering or if decoding happens first in Core and the DAC only Renders makes no difference to the end-to-end results of MQA (ignoring Roon’s optional DSP features for this discussion). Both approaches have the same level of accuracy.
I can even see an argument for preferring the a division of labor between Core and the DAC. MQA Core Decoding is a CPU-intensive task. When it is left to the DAC, the internal XMOS transputer will draw more power from the DAC’s power supply and may emit more ultrasonic noise. Depending on the quality of implementation, this could slightly degrade the analog output of the DAC vs having Roon Core handle this heavy lifting.
It’s best to experiment, but if in doubt, I would steer folks towards leveraging Roon’s MQA Core Decoder even when using a DAC that’s capable of MQA Decoding.
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One thing to remember is that rendering always upsamples to the maximum capability of the DAC. Even though the DAC may indicate MQA or ORFS 44.1 kHz, it’s actually playing at 176.4, 352.8 or 705.6 kHz (4x, 8x or 16x, depending on the DAC). The MQA standard says to display/report only the source bitrate, not the actual DAC rendered rate.
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Ah. I remember reading something about that in iFi’s implementation, but I was not aware that it was standard behavior. MQA is such a mess. LOL.
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@David_Snyder Thanks again for you extremely well explained MQA post above. What a sausage grinder MQA is! It seems that unless one has a MQA DAC, that there’s not much incentive to pay extra for the MQA tier. Once upon a time I owned the DirectStream Junior which was MQA capable, though at the time I couldn’t hear a difference between letting Roon to it’s MQA thing vs sending it all to the DSJ.
On paper, Quboz appears to be a more straightforward Hi-res option with 24/192 being 24/192 start to finish, sans all MQA incantations. Interestingly, WhatHiFi gives Tidal it’s highest marks with Quboz getting a C grade. They claim Tidal sounds better, though they don’t explain exactly which incarnation of MQA they’re using.
I hope Roon puts you on retainer as Global Ambassador and Explainer In Chief!
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The zen stream is only a streamer. So you should connect it to a DAC & amp, or an amp with DAC to stream Qobuz or Tidal
This answer is to Dancing Sea dated Dec 25
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Eureka! I didn’t realize the Zen Stream must be connected to the stereo. This explains the root of my issues 
I’m kidding…
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I’ve read that cables don’t matter. Perhaps my approach of no cables whatsoever has been too fundamentalist
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Maybe you need to return to basics?
Two tin cans and a piece of string?
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Using no cables has reduced noise to zero
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If you use Roon, then native Qobuz support in ZS is not necessary. When using ZS as a Roon transport or bridge, the Roon core takes care of the Qobuz and Tidal Connection.
I planning to buy the ZS later this year and use it dedicated with Roon.
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Yes, of course that is true. But iFi claims Quboz support without Roon. I’m yet to see how that can happen in high res because AirPlay can’t do high res.
@Dancing Sea,
Were did you find the Qobuz support statement? The Ifi ZS product page mention more than ones Tidal support. But there is no mention of Qobuz support.
Maybe Marketing blabla, because Qobuz trough streaming it from you mobile device with Airplay to ZS is not what you can call native Qobuz support.
John we had this discussion on another thread a little time ago and the only answer we came up with with thorough Airplay on the iPhone after removing the promised Chromecast support.
They (Zen) have also updated and removed things on the web page before now. Our guess was it was to be originally provided through Chromecast and Airplay support, but to claim Qobuz support now is a bit disingenuous.
We are not fan boy’s in these threads, but we mostly enjoy the Stream warts and all. We have also complained about the poor software experience on many occasions.
One my phone it looked like the same ttead.
you said
“We have also complained about the poor software experience on many occasions.”
Because I’m considering to purchase one later on this year, I’m curieus about what does course the poor software experience… But all reviews says this the best sounding streamer for it’s price and far above.
I’m just looking for an affordable exceptionally sounding Roon Bridge / Endpoint streamer. It should be running Roon stable without hangs and so. I do not care if the other protocols are working reliable or not, because I won’t use it.
Quboz is printed in the included Zen Stream manual as being compatible. Spotify is also claimed.
IFi is being a tad sneaky with those assertions.
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