The one π and two π speakers sound very similar, but the bass extension of the two π is a little deeper. Both make great surrounds or dialog speakers. The two π tower has much deeper bass response than either of them, and makes better left or right channel main speakers, in my opinion.Build them as shown in the plans, with R11 or R13 insulation on three cabinet sides. The towers will also need insulation spanning the cross-section, laying on braces one-third the way up from the bottom and one-third the way down from the top of the cabinet.