Hearing degrades, true enough. But even a 70 year would be able to tell the difference between a live instrument and a recording - even behind a curtain. It's not all about frequency response. In my opinion, microdynamics is more important, the lack of which is a dead giveaway that sound is not coming from a live instrument.
The Absurdity of it All
50-60-70 year old ears stating with certainty that what they hear is proof positive of the efficacy of analog, uber-cables, tweaks...name your favorite latest and greatest audio "advancement." How many rock concerts under the bridge? Did we ever wear ear protection with our chain saws? Believe what you will, but hearing degrades with age and use and abuse. To pontificate authority while relying on damaged goods is akin to the 65 year old golfer believing his new $300 putter is going to improve his game. And his game MAY get better, but it is the belief that matters. Everything matters, but the brain matters the most.