I recently picked up a pair of Sony on ear DR-15 headphones, they have "Sony, stereo headphone, DR-15, Made in Japan" on the outside of each ear piece. The only information that I have been able to find is that they may have been made in 1971. I am curious about the specifications on these headphones. I pulled them apart for cleaning and they looked like new on the inside except the foam lining between the cloth outer liner and the metal inner grill had begun to disintegrate or dry rot. I have been using them at my desk a few hours a week and they are just now beginning to get broken in. The best part is that I found them at a flea market for five bucks. Any help with the specs on them would be a big help. Thanks in advance.