I have heard and owned a lot of subs and the JL Audio Fathom series are super deep and powerful.
Honorable mention to the SVS SB3000 which are app adjustable, have excellent impact and a very likeable tone.
Subwoofers
I'm looking at subwoofers, my speakers are Sonus Faber Olympica III. I have looked at a lot of subs to the point of overloaded. I'm leaning toward REL S812 X 2 due to room size. My living room, kitchen and dining room are open with a 24 foot vaulted ceiling, area is 35 X 25.
JL Audio, Rythmik, PSA, HSU, to name a few have been checked out.
HELP!