REL Subwoofer. Your input requested

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.

I have the REL S/5 SHO and it's terrific, as is the REL connection system, though I did get the REL upgrade cable...

strenckr,
I sent you a PM. 

@strenckr,

The High Level Input on REL subs is not a marketing hype or a gimmick...it works amazingly and provides seamless integration of REL subs with your main speakers.

You didn’t provide your room dimensions so it’s hard to recommend one 212/SE or a pair of say S/510’s. From my experience, two subs are better than one. But then again, depending on your room size you may be able to pressurize your room with one 212/SE.

I am using a pair of REL Carbon Limited’s and couldn’t be any happier. I switched from a single JL Audio f212v2 to REL’s.