dual 18's vs a single 18??? all I can say is rythmik has a very good musical quality to their subs and their amps can be adjusted just about anyway possible w/peq built in. my fv25hp has dual 15's and looks similar to the 3601. my home 15a circuit bows out before I can get that sub by itself to bow out. rythmik recommends a 240v line for it.
Power: Marantz sr7008, NAD C 275Bee x 2, Video: Oppo 103, Samsung 75un6300
Speakers: Focal aria 948, Focal cc900, Klipsch synergy KSF 10.5 Subs: Rythmik FV25HP, Rythmik FV15HP