Why Do Car Speakers Need a Crossover? Without the crossover, all speakers play the unprocessed audio signal, including the frequencies they are not designed for. For instance, a woofer trying to play ...

so which is best to use, the crossover from the amp or from the headunit or from the speakers? or all of them at once just to make sure the signal is right in case the other filter is retarded?my ...

You will need a crossover. You don't want to push high frequencies to the sub, and you want to filter the sub's frequencies out of your other speakers. Since you're not going to bi-amp, you'll ...