you dont need an amp to put new speakers in.. just a subwoofer needs the amp, every car comes with a small amp or theyre self powered. which is why you got those 2 cables that plug into the speakers.. theyre for the power.
I recommend Alpine speakers.. theyre probably one of the best if not the best. Pioneer, sony doesnt make their own speakers.. they just put their name on the speakers that are made overseas. Infinity speakers too, I wouldve recommended pyle if this was back in the day.. they got bought out and since then the quality aint the same. Ive got earthquake speakers in my car, the company is in hayward so if anything went wrong they aint too far, plus they come with free 5 year warranty.