Thank you!
The answer to your first question is yes, largely due to their "deblurring" and lowering the noise in older recordings. My post only dealt with the accusation of LOSSY, which is meaningless, once the loss is below audibility.
The answer to your second question is yes, but for only one of your reasons - slight sonic degradation for people who don't have a decoder AND can hear above 16KHz. The rest of your reasons only become relevant if MQA takes over the world and that's clearly not happening.
Thanks for your reply.
I'm sorry, but the answer to my first question - does MQA provide anything of value beyond PCM - is most certainly
not "yes," since there is no evidence that MQA's deblurring (a) works, (b) is necessary, and (c) is even possible with any recording that contains sources recorded through more than one ADC. As for lowering the noise floor in older recordings, I have no idea what you're referring to. No digital sampling or processing algorithm (except digital noise reduction or treble-lowering EQ) lowers the noise floor of analogue recordings, and plain old 16-bit PCM with no noise-shaping dither already has a noise floor lower than any analogue recording.
Similarly, I would respectfully push back RE the question of whether MQA does anything actively negative.
On the "slight sonic degradation" of undecoded MQA point, I don't think it's about hearing above 16kHz or any particular frequency, because frequency reproduction is about sample rate. It's about bit depth and the noise-floor issues that go with it. The MQA encoding process puts non-random noise/information in the lower bits, which compromises/reduces the bit depth.
Or am I misunderstanding and are you saying that MQA's leaky filters don't really matter unless you can hear above 16kHz? If that's what you are saying, then I understand your logic but I would ask if the aliasing produced by leaky filters (and the potential IMD produced by the presence of those unwanted aliased frequencies) only impacts the very high end of the audible spectrum. I'm not sure about that.
As for my other two points about MQA creating problems by increasing the costs of DACs and in some cases forcing MQA reconstruction filters to be applied to all content played through a DAC, you are certainly correct that consumers can avoid that simply by purchasing non-MQA DACs. However, I would argue that your position in this regard is fairly weak, since the adoption rate of MQA by DAC makers has been far, far higher than the adoption rate of MQA by streaming services (and digital-file vendors). So one's choice in DAC hardware is already notably reduced by MQA, even if one's choice in music streaming is not (given the advent of Apple lossless/HD and Amazon HD, among others).