Reply to question about monitoring subwoofer

so i just inherited for free some Samson Media ONE's from a friend that was giving away. He said that they don't have much bass and I should maybe invest in a subwoofer of some sort.

The speakers themselves don't have another Output on the back, so is there anyway i could hook up a subwoofer to my setup?

Is it as simple as hooking up another 1/4" from my sound card to the subwoofer? Or do monitoring subs even have a 1/4" input? I have no idea,

Any help appreciated as always