Will I need an amplifier for my new alpine car speakers?

I just bought some Alpine SPS-600 speakers for my 2009 jeep liberty and while it does sound a lot clearer than my factory speakers it has this sound to it like the highs are taking over. I've fixed the treb and mid levels but I really have to turn the trebs in to the negatives. I don't believe my jeep gives them enough power so thats why the tweeters are doing all the control and I wonder if an amplifier is needed