I count four line inputs. I found lots of compact mixers which failed by a whisker, and in truth some might have worked, especially ones with a built in USB soundcard for the computer.
Justin is undoubtedly correct that a DJ mixer will be suitable, especially one with USB capability. Only problem is, it's a somewhat large piece of kit, unless Benny is planning on turning one room of Smyth Towers into a full Studio/Theatre/Entertainment Complex. :)
Studiomaster C3 Family would be a more discreet and possibly more versatile solution.