I'm having a prob with our PA cutting out and need to check my cables. I know how to check for shorts but I also need to make sure that we are not using instrument cables in place of proper speaker leads. So, 1) Problem 1 is some of the cables have plastic moulded ends and cannot be taken apart to inspect, is there any way that using a Multimeter would tell me if they are guitar or speaker leads?? Or would readings be the same? 2) One big cable I have has marking "Oxygen Free Copper Cable" - is this likely to be a speaker cable?? Any help appreciated as I'd rather not throw out what might be OK cables!