Car stereo problems? Might be wrong section for this topic...

I have an 800W Sony Xploid amp for a pair of back speakers in my car. The speaker are 115W RMS and the amp is 125W RMS. After blowing my frist speakers i bought these 115W ones and they work fine. However i am using the stock stereo. After having the amp about a month(was doing fine til then), I turned it up loud one day and it cut out therefore cutting off back speakers. I would have to turn amp off and back on to get it to play and everytime i played it too loud it would shut off. I figured it was because i was using a stock stereo but day says he thinks i damaged the amp when i blew the speakers. Any opinions?