So you say 'not true at all' to my repudiation, and then go on to say:
"you'd be hard pressed"
and "the vast majority will percieve no difference"
which is it?
bit rate: yes, as sounds are at the lower end of amplitude within the bit depth, the more 'stepping'/'zippering' occurs to the input waveform since less bits are available to represent the shape of the wave at that amplitude, and so things become more distorted, and the signal noise goes up. similarly, for higher amplitude sounds, the less need for compressing/limiting to remove clipping artifacts, so again, less distortion (though the latter isn't inherent to the signal encoding per-se).
sampling frequency: irrespective of the nyquist theorem, the shape of the wave is different. even if you can't explicitly hear at a base frequency of the overtones above a certain frequency, the waveform is not the same and your ear is not being moved in the same way, period, and relative distortion of overtones with respect to the base frequencies within the nyquist spectrum increases with frequency, so the tonal effect of the sampling frequency on the sound (and net distortion) is diminished as the sampling frequency increases. aka overtones become increasingly distorted to a lesser extent as the sampling frequency increases; banded spectrum (e.g. FFT display) is much cleaner, as a visual example.
both of these can be masked somewhat with dithering, but again, this is introducing noise into the signal, which you can also hear; all other things equal (which they arent), the dither free signal will inherently have less noise and so be cleaner sounding.
I agree that bit rate is harder to perceive, and for most things, this is more important w/r/t multiple generations of distortion introduced by software.. but just because something is 'hard' to percieve doesn't mean it is imperceptible and therefore a net zero, which is what the original post is claiming. whether a net 0.0001 is relavent is a different matter (as I said previously, 16/44 is generally fine, so I'm not in the 'I can totally hear the difference from my monster cable digital edition' camp), but it is not a net 0, and when listening for tambre rather than frequency, quite clear once you know what to listen for.
also yes:
I did a blind listening test for this while in an audio engineering program. Was able to clearly tell 44 vs 96 and vs 192, as well as 16 vs 20 and 24 (though 24 vs 20 was pretty difficult). That was a while ago so not sure if my ears are still as sharp.