VELODYNE 4 SURE. See if you can't trial one from a dealer near and you'll see why. The SPL is a great series. Bass notes are NOTES not thumps. It will blend into your system and your room using the included EQ.
Give the Digital Drive series some serious thought. My experience is that these will transform your speakers to new heights as if you upgraded those as well. Totally awesome. Mine is an DD18 and my room isn't that large. It's a beast but its never is overbearing. It just adds a certain magic to my B&W 9nt's. Of course when it come time to watch a movie, my concrete floor will come alive! I like the remote but never touch it. When the sub needs power, it just gets it!