I'm not that skilled with a computer to do that. What ever the cause the difference is there and it's not only on one player that I detect differences. What I hear is a difference in the bass response, copies being boomier and less flat, and in the extreme high end, copies being a bit brighter or etched.

In most instances I prefer the original. One time I recorded something for my daughter and was listening to the copy and the original and that difference in the treble actually made the copy preferrable, it gave it a raw or more live sound that was interesting.

Many times a stand alone recorder didn't cost much more than a typical CD player and I can't imagine them being able to make a perfect copy. I'm sure it's possible to make a perfect copy but at what price to a consumer would this come.