I have a Alpine SWS-1222D sub. It's a dual voice coil sub that says 2ohm on the back of the sub. At the store i bought it from the sales guy told me that since it's a dual voice coil, and they're ran in series, that it creates a 4ohm load on the amp. Is this true? Because in my amp directions it says a 2ohm load on it will damage it. Thnx in advance.