Other people singing the songs you are currently listening to when sitting across your working cubicle?!?!
With this I mean, How hard are you driving them?
Is someone with you telling you?
Or are you just doing the "flawed" method of placing the headphones in your thighs or something and try to listen yourself?
If you have a recorder (either video or audio in your phone), turn off everything in the room (AC, fans, computers, etc.) and just plug the headphones into your MP3 player, blast your music and record... or try to find someone else to tell you... Do the 1540s leak like the Denons? Nope. Do they leak quite a lot for being closed-backs? Yup. Pretty sure you couldn't use these for recording purposes...