A crossover and a filter are the same thing. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gifthe passive crossover separates frequencies to the woofer and tweeter and the hu crossover or amps xover acts as a filter,you need some type of high pass filter unless you will be listening at low volume all the time