Keep in mind also that in many (most?) cases MQA will be taking a finalized digital master - essentially what you buy from hires stores - and applying their deblurring plus origami and giving you an MQA file that is (hopefully) much smaller and will be decoded back to standard PCM (internally in the hardware at this point).
You might say that this filter includes optimizations for the recording chain. I would argue the cases where it does are few and far between, simply by the fact that recording chains, ADCs, etc are either not known (most cases), are a digital mix of a many recording chains (many microphones, mike preamps, and ADCs), etc… So the concept of tuning to the recording chain is frankly a bit coocky when you think about it for a minute or two.
So all in all this is a filter, however complicated. I am not an expert in the entire suite of digital filters possible obviously, but this is science and if you tell me Meridian/MQA/Bob Stuart have discovered something noone else had seen before, I will be very skeptical. If you tell me that they have discovered that certain combinations of known digital filters - with specific parameter choices - sounds very good and improves the sound, then I would believe that.
Bottomline:
1- I am all for MQA for streaming
2- I want to be able to use my $25k DAC with MQA by having it decoded in software
3- I do not believe for a second that MQA has uncovered untouched territory in the field of ADC/DAC… But happy to be proven wrong
4- Roon is the perfect tool/place to add the provenance info for a post-processing digital filter that would both incorporate the majority of the MQA post-processing fine tuning and would work with any DAC
Let the science begin!