Did i damage my head unit?

A little while ago i replaced the stock head unit in my taurus with an aiwa cd player. I had planned on replacing the speakers next, but before i could do it, i blew out my front speakers. The rear speakers weren't damaged. The problem came when i replaced the front speakers with a pair of pioneers. at a really low volume level everything seems fine, but as soon as i turn it up, it gets staticy. Or maybe it's clipping for some reason, i don't know. It does this to all of the speakers, even the rear. So my real question is: did i damage my head unit when i blew out the front speakers??? Any help would be greatly appreciated. The car is now my ex's, but she's getting on my case about fixing the stereo. Thanks.