Before you get too involved blaming your stereo, you might want to first check your battery. I,m taking care of a lot of subies, and a few alts go out starting with noise and feedback on the dash. Sometimes the main power cable from the alt needs to be replaced.
The only chronic alt killers have all turned out to be broken and shorting plates in the batteries. This starts destroying your alt every time you hit a bump.
They don't make an affordable rough service battery for a car, so about all you can do is make sure that your battery is securely fastened. If you do not, or haven't off-roaded, this is probably not your bother, but if you do, swap the battery and see what happens. It's hard to test for a broken plate because, as long as it is contacting, the voltage and load tests will read normal.