NissanMax

Hi i have a nissan maxima 2000 and i had it playing on high bass and for a while. i dont have subs in right now or anything im just now starting to hook it up. But basiclly i think they are busted. I can play music low like on vol 20 but any higher it makes a sound like the speakers are gonna blow or something. It only happens when bass parts comes on. Just bought new Kicker 6 1/2 door speakers and a new head unit and it still does it. Ease help me someone.