With the Numark C3 USB you can mix on 5 channels simultaneously. You connect your turntables to 1 of the 3 phono inputs. CD and media players connect to 1 of the 8 line inputs. The mixer receives signals from your PC or laptop via the USB connection. This makes it possible to record a DJ set via your PC or laptop. You connect 3 microphones to the mixer. This allows you to use the mixer in a small karaoke setup. You work the mixer neatly away in a 19 inch rack with the rack ears.