I've been following this thread since last summer. Decided to buy the KEF M500 based on most of the positive feedback. I thought the M500s were going to be the "be all, end all" in my search for a portable headphone to use with a MacBook Pro. It would have ended there until I found out about the B&W P7. Last weekend I caved and bought a pair hoping the M500 would best them. As of right now I can't decide which sound signature I prefer. When I first listened to the P7s I thought I had set the equalizer in iTunes to Treble Booster. Having previously owned the P5, I was not expecting the P7 to sound so bright. I was also expecting the P7 to have more bass than the M500 but I think the M500 has more bass when I listened to "Thunderstorms" by Dr. Jeffrey Thompson. The P7 seems to upscale better than the M500 when plugged into my HeadRoom Desktop Amp. The biggest difference I noticed between the M500 and the P7 is the midrange. The M500 midrange is more forward, making drums have more impact. What's strange about the M500 is sometimes I think they have a little too much bass. Then there are other times the upper midrange/lower treble sounds slightly harsh like when I was listening to the album "Insect Concertos" by Lang Elliott, Wil Hershberger, And Ted Mack. I think the M500 is more portable because the carrying case offers more protection. In terms of aesthetics, I prefer the P7s. It's also worth mentioning the P7s and M500s are very comfortable. I have a little over a week to return the P7s to the Apple Store. The more I listen to the P7s the more I like them so I will probably keep them (and the M500s too). They are both great headphones.