No, you do not need an amp.
Speakers Front: 2X Alpine SPS-610C
» component speaker system includes two woofers, two tweeters, and two built-in crossovers
» 6-3/4" mineral-fortified polypropylene woofer cone with rubber surround
» woofer fits 6-1/2" and 6-3/4" speaker openings
» 1" silk dome tweeter
» power range: 2-80 watts RMS (240 watts peak power)
» frequency response: 70-22,000 Hz
» sensitivity: 88 dB
Speakers Rear: 2X Alpine SPS-610
» Same specs as above
Sub: Powered Subwoodfer Sound Ordnance™ B-8PT
Head-Unit: Alpine CDE-HD137BT
» built-in MOSFET amplifier (18 watts RMS CEA-2006/50 peak x 4 channels)
So with that set up, do i need an amp to powerup the speakers? The sub is already powered.The headunit will provide 18W RMS whereas the speakers are rated for 80W RMS.
As youcan see my setup is not crazy, its pretty decent, something better than stock. So if i do need a sub can you guys tell me which one would work best. The one that is decently priced and available from crutchfield.ca. I would love it, if the amp was small in size.