Overdose said:
Sound engineers are still human and don't have special hearing abilities, just an affinity for that type of work. If anything, prolonged exposure to elevated 'noise' levels in the industry would actually have a negative effect on hearing.
I wasn't referring to "sound engineers", I was referring to mastering. Not all of them work at elevated levels in the studio, or at least, levels that result in prolonged damage.
The point is that I'd guess some could discern a difference (I personally can't, even down to 192kbps), particularly where they work in the industry and close up to the detail in a recording.