I have been waiting to pull the trigger on these for the last couple days and been looking at the feedback on here and other forums. It's certainly a mixed bag but I would expect it on a headphone such as this where it's trying to serve more than one purpose by delivery top sound quality whilst isolating outside noise. I know based on previous experience with B&W headphones they need burn in time, so I am not surprised to hear that the sound does improve after a while. I am still undecided on whether to go for these, I had the Sony m1000x before but just couldn't get used to them, great noise cancellation but wasn't too impressed with sound quality and comfort. However, if the consensus is the PX's score better in these areas then it could be a decider. I am also interested to hear feedback on how they measure up in terms of sound quality against the P9 - I am not expecting them to trounce the flagship headphones but intrigued how close they are.