There are number of cabling options, so it depends on what you pick. The sub amps I use have RCA inputs, but there are other models (same brand) with XLR inputs. I also use the high level inputs into the sub amps from my line stage, so the subs are independent of my speakers that play full range. I happen to have two outputs from my line stage, but if I didn't I could use a quality splitter, but I tend to stay away from those things. The sub amps also provide for a low level input for connecting the speaker mains directly to them. I plan on trying this method, but the manufacturer recommended to me the high level inputs. Another recommendation, was adding quality custom filters in-line with my power amps to limit the bass frequencies going to my speakers, so passing that part is the job over to my subs. I tried this for a while, but preferred my original setup.
So, it depends. My opinion, is that you need to match the proper type of sub(s) to your room. How a sub loads the room becomes important. So, a swarm system as mentioned may do the trick for you. I have even heard of mixing up the types of subs. Luckily, I got really good advice from a couple of knowledgeable Goners and what I wound up picking got the job done.
Good luck,
Kenny
