It is unquestionable that MQA alters the sound, and that includes in the audio band. It forces a filter type on the DAC chain that many find unnatural, but music dependent could be beneficial (to some).
They start with the ignorant notion that "pre-ringing" is bad. If you know what "pre-ringing" is, you will know what this is not a sound theory, and that square waves don't happen in audio. Then they make the bold almost univeral claim that audio is impacted by a ton of 20KHz bessel filters are stacked in a series. Well maybe that was a bit common 30+ years ago, but not recently, and even then that really was not true. So they claim their filter recreates the leading edge of transients. Only problem is, once the information is gone, it is gone. Unless you know exactly the signal chain that arrived at that signal, you can't reverse it. How do you know intentional equalization versus unintentional band limiting? And at the end of it all, the engineers working on the recording are equalizing anyway for the end result.
They start with the ignorant notion that "pre-ringing" is bad. If you know what "pre-ringing" is, you will know what this is not a sound theory, and that square waves don't happen in audio. Then they make the bold almost univeral claim that audio is impacted by a ton of 20KHz bessel filters are stacked in a series. Well maybe that was a bit common 30+ years ago, but not recently, and even then that really was not true. So they claim their filter recreates the leading edge of transients. Only problem is, once the information is gone, it is gone. Unless you know exactly the signal chain that arrived at that signal, you can't reverse it. How do you know intentional equalization versus unintentional band limiting? And at the end of it all, the engineers working on the recording are equalizing anyway for the end result.