j0hnnyI don't think ear pad matters much when it comes to sound leak. TH-X00 leak sound because there is a gap between the wood cup and mounting bracket. The gap is designed as bass tuning so if you cover it it will change the sound signature.
You're kind of stuck with it unless you mod it by stuffing the internal with sound dampening material (but it will definitely change sound signature) so your better off getting a different headphone with less sound leakage.
(Coming from a guy who mod the the Denon AH-D2000 for several years until finally buying TH-X00)
j0hnny@Hyde nailed it, the TH series are NOT fully closed cans, they are semi-closed and thus leak more than fully sealed cans with leather/pleather earpads.
tdkocentdkocen are you implying they do help reduce noise? I'm in an office setting and while I don't play music THAT loud, sometimes i do jam out and would like to reduce leakage if i can