Bad Sound with Traktor Kontrol S3

Hello, I have a problem with Traktor Kontrol S3. If in Audio Setup I choose the Kontrol S3 in Audio Device, the sound in the speakers sounds strange, very digitized, it seems that it has a filter activated, but in my headphones the sound is good. If I change Audio Device and choose as Audio Device MacBook Pro (speakers), the sound in the speakers is good but no sound comes out in my headphones. PLEASE can someone help me with the problem? I don't understand why with Traktor Kontrol S3 in Audio Device the sound is not good through the speakers and through the headphones