a dual 2 ohm sub can be wired in parallel for a 1 ohm load, or in series for a 4 ohm load. it cannot get a 2 ohm load. the configuration of the sub is what determines the ohm load the amp sees. say an amp may put out 1000 watts @ 1 ohm, 500 @ 2 ohms, and 250 @ 4 ohms. wiring that sub in parallel (1 ohm) would give the sub 1000 watts. wiring it in series would give the sub 250 watts. but for a sub to take different power levels at different ohms is wrong. the AMP will put out different power levels, but the sub wont take more or less just because it's hooked up to 1, 2, or 4 ohms, etc.