Phantom loads can be very difficult to detect even with an AC amp meter.  One of the best ways to find them is to shut down every circuit in the house at the circuit breaker box.  Then use a DC amp meter on the main battery cable to monitor each circuit as they are turned on one at a time.  If there is a phantom load it should be very apparent which circuit it is on.  You can then see which appliances are being used on that circuit, and make sure they are disconnected from the power source when not in use. 

There a few ways to deal with phantom loads, the easiest being to simply unplug electronic devices when they are not in use.   Installing wall switches and using an outlet strip can also eliminate certain phantom loads by truly cutting off all the electricity being drawn by the appliance.