Completely agree with Rodney on value of sub(s) and miniDSP.

FWIW, a BK Monolith will reach 17Hz but at some -dB value. An SVS 20-39PC+ or PB12+ will reach 16Hz at at least 0dB if not +3dB in-room. Even 12Hz is possible again at 0dB not the daft -6dB values quoted by some manufacturers. Depends how deep you want to go.

Chris
Srces: Wiim Pro | OSMC Vero 4K+
Procs: HD621 > G61R > Minidsp DDRC-88D
Spkrs: 7200.2 + 5KC + 5Ks | iNuke6K > USC15 | iNuke3K > 2 x Crowson T108SS
Video: JVC HD950 & 1.9m React3 2.4:1 screen
Room: 5.8x2.8m | Various GIK Panels