Sub Upgrade for Music and Home Theatre

None of the above. I would get a REL or Vandersteen

I second Sugarbrie on the REL. Also check out the Thiel SS2.

The Aerial is VERY good and has great looks as well. The xover built in is very flexable and you can run a sub level in at the same time as a main front in so you can calibrate for both theater and music a little like REL does. The Velodyne is just loud but not very clean or fast and always sounds like a subwoofer. I call it the high end Cerwin Vega. I think you should look for REL as well. Anything at or above the B series but not the Q series. I think the REL is better than the Aerial but you can't go wrong either way.

Take a look at Essex Audio SW-3. Very musical and plenty of power for movies.