Agreed. 1A is way too much draw for being off. I would start by double checking lights inside the vehicle. Check the glovebox, courtesy lights on the doors (my wife has killed 2 batteries with that one), trunk lights, etc. 1A draw seems about right for a medium sized light.

If there's no lights on, pulling fuses, while somewhat tedious, will be quite effective.

I wonder, do you have an aftermarket stereo? Is it wired properly? If not, it may have its own fuse that doesn't sit inside the fuse box that you may want to check out.