Audio Problem

Hello,

i have a Minix Neo X7 with XBMC 13.0.
It works great, movies, pictures, ... (movies with sound works)
But when i open a mp3 the sound scrapes extremly. I connected mx player with my xbmc and there are no sound problem in my movies.
Then i thought the mp3 is broken, but when I open the mp3 with another player it works great.
I changed the Outputs between analogue, optical und HDMI without effects.
Do anyone have a idea? Can I changes the codec oder connect a other music player?

Sry for my bad english :/