Aftermarket radios can be a battery killer.
Starters don't have trickle drain problem. Alternators do.
Easy to figure out. Get a inline amp meter and monitor the current draw with all hooked up. Do not try to start car or run anything other than have door open. You can blow the meter. Then unhook the alternator, see if drain goes away.
Yeah, I just moved and my amp-meter is MIA until I go through everything more thoroughly. Stock AM radio right now, I haven't gotten around to swapping it out.
