You are driving down the road listening to some sweet Yanni tunes when all of a sudden his awesomeness is disturbed by scratchy pops and hisses! Well this simply will not do. Now, the problem could be a couple of things but for the sake of this article, we need to find out if the amplifier is to blame. The amplifier in your car stereo system performs a basic function. It takes whatever signal your stereo unit is putting out, be it a radio signal or a CD or whatever you are playing and boosts the signal going out to your speakers. There are usually two major problems that effect power amps so I've split the troubleshooting up accordingly. The power problems might require the use of a voltmeter. You can find these at your local Radio Shack or electronics shop. Be careful working around you car's power, it can jolt you good.