Power Sound Audio - Long time customer and AVS forum member, ahblaza, posted his review of a three V1801 subwoofer system in his room with concrete floors. He sums up his experience
LD Systems CURV 500 AVS Portable Array System AV LDS-CURV500AVS
SB-1000 Pro Subwoofer Receives AVS Forum's Top Choice 2021 Award – SVS
Placing subwoofer inside cabinet to hide. Bad idea? - AVS Forum | Home theater subwoofer, In wall speakers, Inside cabinets