Vinyl sound in bypass bad

I'm using MixVibes Cross on a MacBook and the U46MK2 interface. When I play normal Vinyl via bypass, the sound is superbad (no bass, etc). The U46MK2 is switched to Line, like written in the manual, the software-configuration is set to phono-input. How can I improve the sound?
Thanks
Helge
Thanks
Helge