Using a single active subwoofer

Me again - another of my questions!
I'm looking to get a single subwoofer, with built-in amplifier, to give my system a bit more power, and a bit more boom!
However, I'm not sure how I'm gonna connect it up. I have single outputs from each of my active speakers, but I feel that it's not right to use one of those on a stereo system.
My main mixer is a live performance mixer (Mackie DF-6) beacause of my karaoke and occasional live singer setups. It does have a monitor output, which I can set to any of the channels, including the one from my laptop. Could I use the monitor channel to send a signal to the bass subwoofer? (There is not a problem with the signal, as the subwoofer has a crossover which eliminates the high frequencies).
I'd be grateful of any help here - thanks guys!

I'm looking to get a single subwoofer, with built-in amplifier, to give my system a bit more power, and a bit more boom!
However, I'm not sure how I'm gonna connect it up. I have single outputs from each of my active speakers, but I feel that it's not right to use one of those on a stereo system.
My main mixer is a live performance mixer (Mackie DF-6) beacause of my karaoke and occasional live singer setups. It does have a monitor output, which I can set to any of the channels, including the one from my laptop. Could I use the monitor channel to send a signal to the bass subwoofer? (There is not a problem with the signal, as the subwoofer has a crossover which eliminates the high frequencies).
I'd be grateful of any help here - thanks guys!
