do i need an amp to make my car stereo work?

[stylestealth]

when you install a amp , the speakers wireing all go to the amp instead of the deck, so all of your speakers are wired to the location where he had the amp. what you can do is re route those wires back to the new deck and wire them to the back of the new deck, hook up the hot [red ] and ground [black ] and you will be good to go

[Victoriano]

most likely the output to the speakers are burnt out and that's why you need an amp to make it work

[stylestealth]

when you install a amp , the speakers wireing all go to the amp instead of the deck, so all of your speakers are wired to the location where he had the amp. what you can do is re route those wires back to the new deck and wire them to the back of the new deck, hook up the hot [red ] and ground [black ] and you will be good to go