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Old 3rd December 2018
Gear Head

Originally Posted by sumskilz View Post
So I realized that with the ADI-2 Pro results there is an opportunity to figure out what is being prioritized by Audio Diffmaker, since there are four results from the same interface which only differ according to which filter was chosen.
This may just be semantics issue, but I wouldn't characterize Audio Diffmaker as inherently prioritizing one aspect (e.g. linear phase vs. minimum phase) of the conversion over another. Rather, I would say that certain aspects of the conversion, or in this case, certain filters have a greater contribution than others when it comes to affecting the transparency of the conversion.

Moreover, since I believe Didier is ultimately relying upon the Matlab script for the actual results that are published in the ranked list, it is that script that is most relevant.

Here is my understanding of what is incorporated in that script and the underlying premise (I'm sure if I'm mistaken it will be instantaneously called out)

The underlying premise is that if the DAC and ADC combination are perfectly transparent, there are ONLY two differences that should be observed in the recorded .wav file that is produced by this test protocol:
1. The resultant .wav file could be shifted in time from the original .wav file, and
2. The resultant .wav file could have some offset in amplitude (perfectly flat across frequency) based upon level settings used.

Consequently, there are only two adjustments that are performed in the matlab script, one to align the time of the recorded and original .wav files and one to align the amplitude of the recorded and original .wav files.

Again, if the DAC/ADC combination are perfectly transparent, then the two files should be exactly the same after these two adjustments are made. ANY phase distortion and/or ANY variation of magnitude vs. frequency of the conversion will result in a less than perfect match, which is all that this test is attempting to characterize. Certainly it is reasonable to assume that all of the filters available in the ADI-2 are imperfect and it is also reasonable to assume that these filters won't all have the same affect on the ultimate transparency of the conversion as measured by this script.

Now, how all of these less-than-perfect conversions translate into perceived sound quality, is of course another matter entirely and one that will be debated endlessly. Ten thousand years from now, when the humans have succeeded to destroy most all of the life on earth except for cockroaches, the cockroaches will be arguing about the relative merits of vinyl vs. digital and comparing the size of their DACs.