as others have said, when you look through the grills, the thing that looks like a speaker is actually the back of the very same driver that is playing in your ear. The reason you can hear it is the same that you can see it, there is nothing blocking the path for the sound to get out. The only way to change that is to cover up the grill somehow. The trick is that you can't really do that without dramatically altering the sound. Headphile sells wooden cups you place over the grills, and supposedly they sound good (I've never heard one personally) but they do change the character of the sound. Some people really seem to like the change, so it's considered around here as an upgrade--not really a fix for the "problem" of being an open can. The better solution is to sell your 650s and buy a headphone that is closed such as Beyerdynamics. If you look at Headroom's site (headphone.com) they specifically categorize 'phones into open, closed, etc types. Hope it helps. By the way, you should never listen to the 650s at such a volume that the music is clearly distinguishable from more than approx a foot or two away. Personally, I use my 650s at work in a cube-farm and have never had anyone even mention they could hear them.
