I feel it is best to either purchase one of CA own Subs or getting something that is darn close like the Jamo
. If you don't want to go that route, or want something bigger, I'd recommend a Sub that plays up to 150 Hz and beyond. Otherwise, you would be creating a gap between the satellites and Subwoofer. It is best to stay with one of the previously mentioned Cambridge Audio Subwoofers for the best blend.