You have invested quite a bit of money, more than you would like to admit, into your audio equipment, yet with as much money as you have spent on your sound system, the quality of the audio is not what you were hoping. The reason for this is likely that you have not implemented the use of a crossover. A crossover is used as an electronic filter that ensures that your multiple loudspeakers can cater to a different frequency band, enhancing the audio quality of your sound system. Fortunately, you do not have to pay an arm and a leg to get your hands on a quality crossover. There is a huge selection of these audio components to choose from on eBay. Maybe you need a three-way crossover. Perhaps you are looking for an active crossover rather than a passive crossover. Whatever your needs may be, you are sure to find exactly what you are looking for being offered for sale by a vast number of reliable sellers.