ButtKicker brand products can still be used even if your audio video system does not have a separate subwoofer output if you are using a TV, TV plus soundbar without a subwoofer output, or a gaming console connected to your TV and / or soundbar without a subwoofer output.
Instructions for connecting to an a/v system that does not have a subwoofer output can be found here.
Instructions for when you are using a gaming console and do not have a subwoofer output can be found here.