I don't remember offhand what the 707 is,but if it's got MIDI too you're in business.Program your stuff,hook up the MIDI out of the 707 to the Alesis MIDI in,and go to the menu or page where you can assign the MIDI Note Numbers.You want to align the numbers so that when your 707 sends out a note message for say snare,you don't get the Alesis playing handclaps etc.Most machines Manuals have a chart showing which Note Numbers play which sounds.You probably won't have to change all of them,but there will be some differences between the 2 machines.