There is a diff btw stereo and mono subs, just try it and listen. Mono has more power and authority, but stereo sounds more natural, to me. You didnt tell us about your room? I've found that my 23x20ft room really needed a sub on the other side from the first sub and mains. Nothing else added the right sense of fullness. That's like a mini-swarm. Room treatments certainly helped, but not nearly as much as moving that 2nd sub away from mains.
If that's true for you (large room), then mono should be best. I use option 4, 2 -15 subs (xover 40) in stereo near the mains which are not xovered, and a single 10 driven mono and xovered a little higher (57hz) to help load the room with the mains. Someday I'll try a 4th and run it as two pairs in stereo.
Stereo vs mono can be done with speaker or preamp. All mine run on preamp. Main amp is driven xlr from dac, and use rca spltter for subs. Each 15 gets a single cable, and 10 get two for mono.
RELs disappear so well bc they use speaker outs which lends the main amp sound to the subs. It's a really nice effect, but I prefer the cleaner, tighter sound of the preamp outputs. As always, the quality of the interconnects and power matters a lot, and especially for the subs to xover to mains. That's the drawback of doing a swarm my way, you need more good cables. It's all tradeoffs, best of luck and let us know what you tried.
If that's true for you (large room), then mono should be best. I use option 4, 2 -15 subs (xover 40) in stereo near the mains which are not xovered, and a single 10 driven mono and xovered a little higher (57hz) to help load the room with the mains. Someday I'll try a 4th and run it as two pairs in stereo.
Stereo vs mono can be done with speaker or preamp. All mine run on preamp. Main amp is driven xlr from dac, and use rca spltter for subs. Each 15 gets a single cable, and 10 get two for mono.
RELs disappear so well bc they use speaker outs which lends the main amp sound to the subs. It's a really nice effect, but I prefer the cleaner, tighter sound of the preamp outputs. As always, the quality of the interconnects and power matters a lot, and especially for the subs to xover to mains. That's the drawback of doing a swarm my way, you need more good cables. It's all tradeoffs, best of luck and let us know what you tried.