I know I can hear down to 25Hz with headphones so the 64Hz limit seems weird to me. I have no probs with the upper limit - I know mine used to be > 20kHz when I was (much) younger but it's now ~ 17kHz. Mattias_ka, have you heard a CD from the labels that I mentioned?
64Hz lower hearing limit for humans?? Mattias_ka, I suggest you go and listen to a CD from a brand like Chesky or Reference Recordings - the dynamic range is huge.