Back in my long era of speaker only listening it become clear that speakers using sheets of mylar had really long break-in periods. My prior two cans with some resolving ability were the HE-500 and HEX v2 (both used), so I just didn't account for the importance of break-in of the HE6SE. Manual says break-in is at 150 hours. For me lots of changes between 50-90 hours, so we'll see. Very promising.