I've been using the blacks over the 2's since getting them this week and noticed that my left wasn't sealing as well as my right. Having said that I really have been enjoying them and went through a number of tracks on you tube last night instead of getting an early night. Still getting a decent amount of isolation on these as well though. Had the fire alarm being tested at work on friday (being checked over for service, so it kept going off) and was loud enough for me to notice it, but saw everyone else wincing. Took the left ear piece out and was a bit surprised at how much louder again it was and quickly put the left back in. It's going to be a bit of a wrench sending these back for refit but at least it should be a straight forward one this time (I hope!).