Hello good people: My CB-10's are the biggest woofer I am running right now (along with baby advents and AR 102's both with 6.5" woofers) but feel I need a little more bottom end bass , and after scouring ebay and other auction sites I see I can buy all the drivers I need to piece together a decent KLH system, model 5  12" woofers mids tweets and crossovers cheaper than a complete speaker set..  DO any of these companies (AR Advent KLH etc.) make a stand alone sub??) What makes th