engine doesnt turn

Hi, I've recently replaced my battery, starter, and alternator, but the car still isnt starting. The problem I think is, is that the altenator isnt putting any power into the battery, so I'm guessing its the wire inbetween the two. When the car is jumped it starts, but after that, nothin. Can anyone give me any help?

do you have an aftermarket sound system with a possible short somewhere, that would cause the battery to instantly lose all its starting power once the engine is shut off???

No, all original audio equipment.