January 31, 2012 8:35:24 AM PST
Running active is when there is no external passive crossover network between your speakers and amps. The passive crossovers limit the potential of a speaker while at the same time they protect them from receiving frequencies that aren't meant for either the tweeter or what have you, among other things, not all passive crossovers are created equal tho, some have more functions than others. Generally running active requires some type of DSP to set crossover points, volume and time alignment of each independent driver, running active also usually leads to a louder and cleaner sound.
