Before connecting the subwoofer, always switch off all your equipment. Pre-Out connection: Use an RCA cable to connect the Pre-Out output of your amplifier/active speakers to the input on the subwoofer (both L/R). Sub-Out connection: Use a subwoofer cable to connect the Sub-Out output of your amplifier/active speakers to the input on the subwoofer. If your subwoofer has both L/R inputs, you only need to connect to one of them – which one doesn't matter. If your subwoofer doesn't have any of the connections we just mentioned, you will need to connect the speaker cables from your amplifier to your subwoofer, and then connect your cables from your passive speaker to the bottom connections on your subwoofer. Wow, that's a lot of words for such a simple connection! Anyway, now you can finally connect your subwoofer to a power source.