I am really new to automotive audio, all I know is impedances have to match and too many watts will blow speakers out. I have a pioneer DEH-P3300 head unit I got from a minivan and I've been wanting to upgrade my sound system a little. I like to feel the bass, but not to the point of vibrating body panels and being heard several cars away. The radio specifications say Max power output is 50Wx4 4ohm and 70Wx1 2ohm for the sub output. One of my speakers in the back is already dead so I'd like to replace the speakers all the way around with something nicer than stock but not so nice I'll go broke buying them. Can anyone suggest what the specifications should be on the speakers? Can I hook up a sub directly to the head unit or do I have to go through an amp first?

Here's the radio's manual
http://www.google.com/url?sa=t&sourc...F4h_DKQEN6U6JA

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Black 1996 Ford Ranger XLT 3.0L V6 2WD - blue LED underbody neon, blue LED backlighting in headlights and reverse lights, blue EL wire in side emblems and grille emblem, blue LED under-dash lighting, custom 1/4" steel tubing rear bumper, Diamond plate toolbox, dual 4' Fiberglass CB antennas