mp3 player question regarding sound

what affects how loud the music from an mp3 player? the mp3 player itself or the headphones? and how do u determine how good headphones are? like how do they measure how loud they play? for example in stereo systems its called watts.

any help appreciated thx

what affects how loud the music from an mp3 player? the mp3 player itself or the headphones? and how do u determine how good headphones are ?like how do they measure how loud they play? for example in stereo systems its called watts.

any help appreciated thx

arr1023

what affects how loud the music from an mp3 player? the mp3 player itself or the headphones? and how do u determine how good headphones are? like how do they measure how loud they play? for example in stereo systems its called watts.

any help appreciated thx

arr1023

what affects how loud the music from an mp3 player? the mp3 player itself or the headphones? and how do u determine how good headphones are? like how do they measure how loud they play? for example in stereo systems its called watts.

any help appreciated thx

arr1023