A pro-tip for those serious with DJ and music production is to use a USB audio interface. For this, many prefer Focusrite.
The following is a description of one of their popular product:
Scarlett 2i4 is a 2 in / 4 out USB audio interface featuring two award-winning Focusrite pre-amps and four high-quality audio outputs. Housed in an anodised aluminium unibody chassis, the Scarlett 2i4 is the perfect audio interface for musicians and digital DJs.Amazon.com currently has a special price for the
Focusrite Scarlett 2i4 USB Audio Interface