I understand efficiency and that a more efficient speaker is going to be louder at a given wattage than a less efficient one. I'm asking about the system of an amp and speaker. Some subwoofers have dual voice coils and if they are both 4 ohms you can wire it as 2 or 8 ohms. Will the system, as a whole, be louder if wired at 2 ohms than at 8 ohms?