Know what? For a while now I thought it was a little sub par. I'm a loud listener (90% volume on iPod Touch) and during quieter sections of songs on the subway I could hear the door bell ring, or the station announcements. I was also planning on using these for DJing, and I wans't sure if my mixer would pump enough juice into these to be loud enough to hear them over the monitors blaring next to me, or the bass bins I'm practicly standing on.
Well safe to say, I did a gig last night (first DJ gig ever) with these and I caught myself making the Obama "not bad" face when I put them on both ears and could still feel bass on the side of my head, while still being able to ignore the club, and being able to mix efficiently.
Oh I can also highly recommend these for DJs. The bass impact is GREAT for queing the 'one' beat, and the forward highs helps line up the hi-hats rather nicely.
so in close, some may find the isolation a little sub par, but I used them in A CLUB and it's safe to say they do a good job at isolating for me, and leak is minimal, so you're not disturbing the people next to you on the bus.