dont know bout the dd but i have a fully loaded btl and i was told be better to use 4 4inch to have any high end but i was tuning to 33hz so idk what u are tuning too
SQ= something that accurately reproduces the original recording. To achieve this, the sub system's design must include things like input power, of course its enclosure (size/type/alignment/positioning/etc), and the rest of the system it is to be paired with. You can make a decent subwoofer sound very good if you attack all the variables with equal thought.