Itunes Tracks audio problem

Hi i am Nico,

i buy most of my songs from Itunes and some of them are fine to play. But some of the songs are very quiete and in the middle of the track they get to the normal volume but only for like 4 Beats. This only happens when i play with DJ Equipment wich is plugged in to a Windows Laptop. Also in Rekordbox at home the songs have the same issues. A friend of mine has the same struggle as me. Thanks already for eny advise.

Nico