Hi, I'm new to the world of audiophilia and have been doing some online research that led me to the purchase of a Chord Mojo amp with B&W P7s, after trying the P7s in the shop I was seriously unimpressed - the sound was muffled with very poor resolution and I was somewhat amazed by all the good reviews I had read. Can anyone recommend me a much better alternative? They need to be headphones that don't leak too much sound as I'll be listening in an office but also be reasonably portable. I'm happy to go up to around £4-500 for headphones with truly excellent resolution. Thanks in advance

See if you can try out a pair of Oppo PM-3; portable planar magnetics are pretty cool. Another option that's more "fun" sounding is the Meze 99 Classics.

Thanks a lot, I read some very positive review about the Oppos, will have a look.