For the test the quality of the input does not matter. You can conduct the same test with a beautiful 24-bit recording as source, you would still not be able to hear much in the end.

And that's the point.

When you print a photo in size 9x13cm, does it matter whether you print it in 10,000dpi or 20,000dpi? Hardly, unless you always run around with a microscope.

And it does not matter, whether the photo was originally a good picture or not.