My p6 headphone sound very weak.. plz help...

hi guys
when i update my p6 to androidd 4.4.2 b708 music sound in the headphone in very weak
but in the radio app in work correctly
i install very app like walkman and mx player and other player but its not fixed ..........
i very confused I do not know what to do..
and my device is not root
plz help me
i really need help
thanks