I think PB1000s may be disappointing coming from CSX15s. The Cadence subs have a tremendous amount of upper bass output, many times that of PB1000s. A system with floor standing CWs is intended to get loud, which is something the PB1000s will not do amazingly. On the other hand, the CW tower speakers should be able to do mid bass very well, so if the PB1000s were crossed over low enough, they could possibly make a meaningful contribution to that system since it is tuned lower. But there is no way the SVS subs are going to outperform the CW speakers above 40 Hz.