MQA isn't a codec, it's a process. All of the levels of MQA cannot be unfolded via software.
MQA at the DAC level is not only to unfold (decode) the hi-res according to the sample rate limits of the DAC chip but also to optimise the DAC chip's sound quality by applying a pre-emptive corrective filter to the digital signal prior to conversion to analogue (rendering), that filtering is really the trick for the best sound and why an MQA encoded song sounds best than the equivalent uncompressed Hi-Res studio master song.
Bel Canto's John Stronczer explains it like this:
http://www.digitalaudioreview.net/2016/06/an-inconvenient-truth-mqa-sounds-better/
Why embed MQA into the DAC?
"Using the spline filters you cannot have an apodising filter before or after or else you will compromise the phase and frequency response. You also need to take care with the analog domain filters and ideally any filters after the MQA decoder need to be measured and the MQA filters optimized to take them into account. This will lead to the BEST performance..."
"...A software only implementation could indeed work well but not necessarily at its best, and in the worst case it could actually lead to excessive phase and frequency response errors in some DAC and system applications, so it DOES actually make some sense to control the process in an approved platform and optimize each companies' or even each products' filters for best performance, further differentiating any MQA product from another. In other words a specific licensed spline filter will be unique to each design and company."
As mentioned by Stronczer, the pre-emptive, corrective filter is customised by MQA (the company) according to the fingerprint of the DAC chip, its own filters and (sometimes) the D/A converter’s output stage as measured by MQA. Note that Stronczer also suggests that a software decoder is possible but also probably less effective. One implication for DAC manufacturers signing up for MQA certification is that Bob Stuart's team will need to recalibrate the filter each time a change is made to the DAC design – e.g. a move from Wolfson to ESS chips means fresh MQA code will be required. FPGA DAC developers whose changes come thick and fast via software updates might see this scenario as less than ideal.
Without MQA in the DAC, no un-folding takes place – only the first 44.1kHz or 48kHz is parsed – and the pre-emptive filter correction isn't applied. Only the MQA encoding process is heard.
"Does MQA encoded music played back on a non-MQA DAC sound better, worse, or the same as playing back the file in its native resolution? While it depended on the recording, un-decoded MQA file did not sound worse than the original native file and in some cases, the un-decoded MQA version sounded better."
Tidal Hifi subscribers with MQA-capable DACs get the double whammy of a full hi-res stream decoded by an MQA-optimised signal path. Those not in possession of such hardware will, based on my listening experience, see an uptick in sound quality without lifting a finger. Or wallet.
Remember: MQA playback is a two part process in a suitably-equipped DAC: 1) hi-res unpacking (decoding) and 2) pre-emptive filter application and decoding (rendering).
I'm willing to bet the latter is why all hear better sound quality from an MQA file than the hi-res original. MQA seems to do a better job of making the three dimensional illusion that is high end audio playback more believable.
MQA isn't a codec, it's a process.
And that process begins at the studio. The MQA algorithm corrects time domain inaccuracies (pre- and post-ringing) caused by the original A/D converter. This is either done at the studio, soon after the recording is made or, for existing recordings, with one of the handful of MQA-equipped computers dotted around the globe.
The implication being that MQA can potentially correct the temporal smearing of almost every recording in existence. Success here largely depends on whether the original A/D converter's make/model is known. If it is known, precise settings can be applied, otherwise a best guess filter is applied.
More info, reviews and test about MQA:
https://www.audiostream.com/cont ... 8lrrXAcBxwvqzfUE.97
But the main problem with MQA is that MQA means handing over the entire recording industry, its a propietary technology, not open, not standard that needs DAC modifications which has licensing fees, software modifications to decode MQA which has licensing fees, special MQA recordings and process from the recording studios which has licensing fees, also studio recording equipment with MQA technology with licensing fees, more licensing fees from all the digital audio product manufacturers like FiiO for any individual unit sell, and royalties from any indivual purchases of releases by the recording industry for any individual album sell.
Also MQA rights not allow to output the decoded audio via any digital output from any digital audio equipment. Is limited.
Sorry but MQA has no future. The next posts is about MQA from the most important audio engineers and companies:
http://www.schiit.com/news/news/why-we-wont-be-supporting-mqa
https://www.linn.co.uk/blog/mqa-is-bad-for-music
https://positive-feedback.com/au ... rview-andreas-koch/
https://www.computeraudiophile.c ... timized-hires-flac/
In summary,
Has MQA best sound quality than Hi-Res files? Yes.
Is MQA the future technology of playing audio? Most likely not, will be very expensive because MQA is a propietary technology, not standard, not open, and wants to takes control over the entire recording industry with a very large number of licenses fees to be paid for by all parties involved with any unit (DAC, Player, Recorder, etc.) or album sell.
If in the future MQA is not successful,
what will you do with all the music in MQA that on non-MQA devices and players sounds worse? At present it is better to guarantee your library of music in Hi-Res that always plays in the future in every device and any player.