As my handle would suggest, I'm a professional piano tuner. I have been a rock musician and concert goer since childhood, I'm 47 now. Sometimes I'm surprised how many of my customers simply cannot hear the tone produced by the highest notes on the piano. Often these are people not too much older than me and with far less history of abusing their ears than I have. Maybe I'm just lucky, but I can discern the effect of high frequency in the music I'm listening to quite clearly. I'm not sure what the uppermost limits of my hearing is, but I would say that when I listen to good high resolution recordings there is a realism that is brought about by introducing as many of the frequencies, or as broad a range of frequency, as occurs in a live situation. The interplay between the frequency range that most people an hear and the stuff above and below that, all play a part in creating a more realistic reproduction of a sound, and that's the ultimate goal for a good audio system. My system I think has a range up to about 40khz. Even if I can only hear a quarter of that, I can hear the effect of the high frequencies that are there in my high res recordings. I would also say that after a few years of listening to high res stuff, my CD quality and below all sound a bit compressed and limited by comparison. I'm not saying I don't enjoy CD's anymore, but I hear a clear difference in dynamics and realism with the 24/96 stuff without a doubt, and I believe it's primarily due to the presence of the highest and lowest frequencies. I also have an SVS sub pushing down to an audible 20 hz. My goal is to not hear my system at all, just pure realistic music as though it's happening in my room. I'm sure to truly achieve that would cost much more than I can afford, but my system comes close enough for me to recognize the importance of range.