Adding additoinal subwoofer to system


I currently own a rel storm org.I was wondering if it is possible to a rel storm three or do I need to add the same one that I have now.
jjet
I would be very inclined to stick with one additional sub with an identical hookup or y cable.
I would see no reason they would not work fine. I use a Stadium 3 and a Stadium 2 together in my system.