If your amplifier is 2 ohm stable, then you can power both voice coils using the bridged output, using a 2 Ohms impedence to 'cheat' the power from your amplifier. As Tommycab says, we'd need to know the amplifier brand and model to ensure it's capable of doing this. Anything from a decent manufacturer in the last 5 years or so should be 2 ohm stable (stable, not just capable). Anything from a budget manufacturer (the 8000 watt specials for £69, that type of thing) isn't likely to be able to do it....