It has to be your wiring. Check with a volt meter to see which is the AAC (only on when key is turned) and the constant supply (feed from the battery). Usually a radio draining the battery is where those two have got swapped or there's a leak to ground.
Here's the digram.
https://i.pinimg.com/originals/2e/2f/e6 ... 1b29d7.jpgThen check if you have a leak between the ground and any of the speaker wires, then check there's no short between speakers (i.e. different speakers).
If the wiring is all good then something off with the stereo and you need a new one. Also, make sure you have the right wiring harness for your stereo - using the wrong one could mean that you're shorting out. Again, check the wiring and pinouts on the connectors.