My system was purchased in 2012 and I have a SW-110. I just upgraded my AVI and would like to add an additional sub. I've contacted Klipsch and they advised getting the
R-110SW Subwoofer | Klipsch
Klipsch SW-110 Powered subwoofer at Crutchfield
Build Quality - SW-110 Subwoofer, C-20 Center, and S-20 Surrounds | Audioholics