Most definately the amp can cause a current drain if it is fried. Pull the fuses duh. Anyway, also if your batter is that dead and you just jump started it and took off there is a good chance that it's fried as well. A batter that dead needs to be charged back up before use, I wouldn't be suprised if you cut the life of your alternator in half because it was trying so hard to charge that battery for the short time you drove.