Is it necessary for a headunit to come with subwoofer pre-amp out puts or could u conect a lo-pass crossover to the rca cable for the subs?Thanks

 

most most decks that come with sub-outs have a x-over internally, if you choose to use it..

otherwise it's just a non-fading preout, and they should call it that..


but yes, you can use an external x-over (like the one that'll most likely come on your amp) to low-pass the sub signal..