Bernie glad you r enjoying them.....with an additional TIGHT sounding sub it would broaden your flexibility with the CM30s for sure ......

the ROLAMD KW-1
http://www.rolandus.com/products/productdetails.aspx?ObjectId=557&ParentId=33

or EV SB122 might fill the need for a medium gig 3pc setup for sure.
http://www.electrovoice.com/products/199.html