a lot of the newer HU have real built in amplifiers that require an actual 8 ga wire feed from the battery. If you HU is not like this then it is more than likely putting out half the power it is stating probally less. If you are going to buy an external amp get one from a reputable company. You will be better off and will be getting actual watts not hyped watts. Memphis, diamond, eclipse, jbl, zaptco all come to mind off the top of my head, memphis being my favorite for price and performance. and an amp will make your speakers sound much much better. Good luck and try www.the12volt.com great group of guys over there.