Ah... it's 'addicted'...
About the hissing sound, I think some of us here knows how to solve it. Putting a resistor or what...

actually noise is not caused by the earphone itself.
it's the player emitted noise, while the earphone is sensitive enough to pick it up.
which usually low impedance earphone has this kind of trouble for being over sensitive.
if you pair the earphone with some DAP which is good enough,  (example , Zen Micro, Zune) it won't hiss as the player doesn't produce hiss.

anyway,to slove it, as walabies said, we can add up the impedance (resistor) of the specific earphone, by adding some value (usually 15-100ohm) of resistor in series configuration to the earphone signal cable. or make a adapter like picture below so that you doesn't have to operate the earphone itself which operating it will void the warrenty. and adapter is better because you can use it for any other earphone too.
* note :  do make sure to hand match the resistor to exact value (as close as possible you can get),  because even as small as 0.1 ohm will have chances to make the earphone sound imbalance on volume for both side.