bad quality recording in rekordbox

Dear people ,

I have a struggle with recording in rekordbox. 
My music is good quality but everytime I record in rekordbox and listen it back, the quality is really bad! You can also see it in the difference in the waveform.
I tried somethings but I can't find a solution myself.
Is there anyone who can help me and knows how to fix the problem? I'd ike to record my mix in good quality :)