Phild Most old wiring from the 20-40's is probably insulated with asbestos and is 16 gauge or 14 if you're real lucky. You are right, typically they were hot and neutral with no ground. You wouldn't happen to have those old glass 15 amp breakers at the service panel? An old trick to keep them from doing their job was to place a penny at the point of contact so the fuse wouldn't blow. I would double check, have seen this often in old homes and is a fire waiting to happen especially if the circuit is overloaded. That wire will get HOT!! I would consider upgrading your electrical service if you own the house. At least for the audio. With the current demands of a high end audio system, running too many components on one circuit is not a good idea. And those old houses didn't have too many circuits, didn't need to back in those days. You also might look at the wire connected to the outlets. They may be worn down and may need to be cut back if the wire is thin at the outlet contact.
