Hearing those artifacts in a 320k file requires intimate familiarity with a state of art recording that features something like castanets or timbales or such. Anyone that claims they hear it right away in every comparison is utterly full of it.You might enjoy Audiophoolery
It also depends on the listener's ability to hear compression artifacts. I've intentionally avoided trying to train myself to hear them... If I'm not noticing them now, I don't want to start hearing defects or to start trying to hear defects!
It is also an utterly unrewarding exercise. Stands in the way of enjoyment for zero valid reason other than archiving knowing that the recording is 100% preserved.