Definitely 6 – That's Zu's new Definition VI [$19'999/pr] aiming for first March shipments. "The ongoing proposition is to deliver maximum musical performance in about 1 square foot of floor space per speaker. Hence Definition VI retains the 13×13" footprint but will be 5 inches taller so 54" without feet. Dual full-range drivers separated by a super tweeter carry over but here is where things begin to change. Version VI uses widebanders derived from Soul VI and a new super tweeter more extended and consistent than the earlier Radian 850, with our machined aluminum phase plug incorporating a version of the compression clamp used in Druid VI. The Eminence LAB-12 woofer returns to the powered subwoofer section now as a front-facing element. The updated subwoofer amplifier now mounts via suspension to further reduce noise. Completely new are construction and first application of Griewe acoustic impedance adaption in a Definition. The cabinet borrows from the engineering investment in Soul 6 by using a stiff relatively lightweight internal superstructure to manage energy dissipation and thwart cabinet talk with less bulk so Definition VI will be about 40lbs lighter than Definition 4. All prior Definitions were sealed boxes with powered subwoofers. The subwoofer reappears but the Griewe scheme used in every other Zu floorstander now applies to each of the full-range drivers. We've engineered an innovative way to implement Griewe via the rear of the speaker rather than floor-facing and incorporated an internal Griewe Gap adjustment so that the widebanders have useful response to 35Hz and the woofer can be more precisely assigned to its true specialty task."