what is the downfall of leaking sound?

if environment sound doesn't matter which is a better sounding headphone?

Would you take the a500 or the 555, or are they equal?

I'm looking for a set of headphones strictly for watching movies and gaming on the PC unamped. I know if I got a good set I would also likely use them for portable mp3 listening, hence why i haven't ruled out the ms-1 or SR80 yet. For these tasks what would be better, the a500 or the HD555...

I've read lots of reviews and I would like your opinions. The PX100 are quite popular for being a really entry level headphone. Since i'm looking for a headphone that is quite versatile, would you choose the PX100 or HD555, Grado SR60 or SR80 or the A500. I dont have an amp and will be using...

I am looking for some headphones that will be primarily used for watching movies / tv (on the PC) and will occasionally be used with a portable mp3 player. I've read so many good things about the Grado SR60 and 80s but i've also heard that for movies they aren't that good, "They are a great...