If your goal is bass that is articulate, tight, fast, powerful, and deep, then the number of subs is far more important than which sub. No one sub can match four reasonably good ones. Nothing else with subs is anywhere near as valuable as if you can learn that one basic truth.
Now as for how its connected, does not matter. If the sub has speaker level inputs that are convenient then use those. Or if the sub has line level inputs that are more convenient then use those. Got it? Nothing matters less than which one you use. Well, except for balanced, which will matter only in the sense it gets you to throw away money on something that's an absolute total waste when it could be spent buying something that's not quite a total waste.
Save your money to buy more subs. Thank me later.
Now as for how its connected, does not matter. If the sub has speaker level inputs that are convenient then use those. Or if the sub has line level inputs that are more convenient then use those. Got it? Nothing matters less than which one you use. Well, except for balanced, which will matter only in the sense it gets you to throw away money on something that's an absolute total waste when it could be spent buying something that's not quite a total waste.
Save your money to buy more subs. Thank me later.