The question was: which side of the switch. TC is only one to answer. I would have said output side, but I don't think it would make any difference electrically unless the switch can only handle 6V. secondly, these resistors have heat sink fins on them and need to be places in fairly open air path, not tucked away. They will not start a fire.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn