I guess I don't understand what they are claiming. They're saying that they're filtering the master quality digital file to correct for errors created the last time it went through analogue to digital conversion? It's kind of like pressing the "undo" button and removing the error and turning it back into the original pristine analogue signal again?
What if the signal had been processed in the digital domain several times since it went through that conversion? Wouldn't that processing muddy the waters and make it impossible to simply undo whatever problem the theoretical error caused? I can't imagine any master delivered by a record company to be a raw transfer directly off an analogue tape master. Every distribution master would have undergone some sort of mastering or restoration or perhaps sweetening since it was digitized.
The only way I can imagine that they would be able to know for sure that a master is a direct transfer with no modification is to do all of the digitizing and mastering themselves. Then they would have control of the process instead of trying to guess what had been done with the signal between the original analogue to digital conversion and the delivery of the master quality file to MQA. Re-digitizing and remastering everything would be reinventing the wheel on a massive scale with the size of the library they are working with. That just wouldn't be practical.
Also, if there really is some sort of "smearing" that they are able to correct by means of a backwards filter, that means that every single digital copy that exists- from CDs to SACDs to blu-ray audio to the digital masters themselves- all have this smearing. No one in the history of digital audio has ever heard music that has been recorded digitally without smearing. And logically, that means that the MQA file isn't just a faithful reproduction of the master, like Redbook, high bitrate lossy and HD audio. If their smear correction is audible, that means a streamed MQA file sounds *better* than the 24/96 digital master itself.
Why aren't recording studios taking advantage of this great technology? All they would have to do is apply the filter along with the analogue to digital conversion and it would improve the sound of the digitization! Why is MQA selling this to consumers listening to streamed audio instead of selling it to Digidesign and all the other companies that manufacture digital audio production hardware and software?
But of course, if you sell technology to sound engineers, you're going to have to prove with controlled testing that it's actually beneficial and explain how it works. I doubt they are willing to do that.
This is why I'm skeptical of the whole format. They make general statements about "smearing" and "authenticating" masters, but anyone who has any kind of experience in this stuff at all can see the outlines of the mirrors amid all the smoke. All of this stuff is in the hands of the label. By the time MQA gets handed the master, they can only work with what they're given... the same way Amazon and the iTunes store and Spotify and every other streaming service does. If there really is a technological breakthrough here, they should be selling it to audio production, not streaming.