J.C. makes some good points, as they are not the same and yes over time the Xcon has evolved gradually. Far more so than any other SSA sub. Yes, the motor force is different due to the soild pole now, the cooling is different as it is not being vented by the pole and the suspension (if still original on the senior model) is different as the spider packs have been tweaked over time. But, they are not so different that they cannot work together in a shared chamber enclosure. Meaning, they have become different over time, but not so different that they are totally unrelated and cannot work well together. They both still have the same coil, nearly the same moving mass, very similar suspension compliance, same top plate and same massive single slug. If this was the Icon or Dcon for example, due to the complete change in the motors, those models are somewhat farther apart in the generation gap. Where as the Xcon has been an evolution, not a generational jump if that makes sense.