When I ran Dahlquist DQ10’s with double Dahlquist subwoofo, the placement turned out to be important for the best imaging. Low frequencies are supposed to be non-directional, but I think it matters depending on your crossover point and the steepness of the high filtering. I thought two worked much better than one for integration, but it made for a physically unwieldy system. I simplified my system, getting rid of the subwoofers when I changed speakers, as I found the system more cohesive and imaging better, even though I lost the bottom half octive.
