Long time audiophile here, but new to the group. I really enjoy reading the reviews Amir puts up.
I am in consideration of a 21" Eminence subwoofer (https://www.parts-express.com/pedocs/specs/290-5662--eminence-nsw6021-6-spec-sheet.pdf) to augment my 4 other Dynaudio subs in a large basement...