i installed a jensen 200watt amp into my truck and i put a 12" 450watt pioneer sub into it and the other day my speaker sounded like it was blowen it was cracking real bad so i hooke the speaker up in my room to my stereo to see if it was the speaker or not and the speaker works fine so i figure its the amp its an old amp i got from my friend but i dunno if it still is the amp or what how can i test the amp??? help please!!!