sound problems with rekordbox

since I've updated my pc from windows 8.1 to windows 10 I expierence soundproblems with rekordbox. the low tones are almost gone when I listen to my tracks with my headphones. I use the sennheiser HD-25 II. There is nothing wrong with my headphones. when I listen music on youtube or beatport I hear the bass on my headphones. I already updated the driver for my soundcard. what can I do?