Persistent problem

I've recently finished up my audio setup and yet i'm still getting problems. I've had 2 different amps on two different speakers and they all make crackling noises, mostly in the tweeters. I haven't heard it in the woofers yet. After checking everything, my only guess would be my car not being able to put out enough power? I do plan on upgrading the electrical. (I still have stock battery and alt) But what confuses me is why do my subs play without distortion though? Any ideas?