Go with two of the Vandersteen subs. Two are the minimum. Never consider just one. IMHO the problem for most commercial subwoofers is their enclosures. When auditioning a subwoofer put your hand on it, any vibration or shaking you feel is distortion. Martin Logan and KEF make "balanced force" subwoofers that are quieter. Another problem is the use of plain low pass filters for crossing over. A complete 2 way crossover removes bass from the main speakers lowering distortion
Looking for a new Subwoofer
I am looking to replace my Definitive Technology Supercube 6000 with a new subwoofer to augment my Fyne F-702 speakers. My listening room is about 13 x 22 ft with 8’ ceilings and an 8’ opening to the dining room to the left of the listening area. I try to avoid major products made in mainland China—in spite of their at times very good quality, and I have narrowed the brands down to Paradigm, Vandersteen, and JL Audio, specifically, a single Paradigm XR11 or dual Defiance X12s, the Vandersteen Sub Three with “required” crossover, and the JL Audio Fathom f110v2. My budget is about $4K, with the XR11 and Fathom right at that price, the dual X12s at about $3K, and the Vandersteen with required crossover at about $5300 (including two crossovers, as they are sold in pairs). I may be able to audition the Paradigms and the Vandersteen; a friend has told me the room correction software with the JL Audio sub is way behind that of the Paradigms. In light of the excellent advice I have received in this forum, I wonder if folks out there have had an experience with these subwoofers and what they might recommend. Many thanks.