Well this is interesting information. The Wilson Sub in Europe is 14500 euro (18000 US$). So I guess I can not afford it. In stead I am willing to try the Velodyne. I guess if you adjust it manually it will be possible to set it at 30hz and if you use the software you will not be possible to do so. With this price of the Watch Dog you can imagine only a few are sold in Europe. Second hand impossible to find. In America the voltage is different so if I import one from America I need to pay VAT (19%), then shipment and modification to 230V. This is going to be as costly as bying one here. How much definition in the bass do you hear at 20-30hz. It is more feeling than hearing. The speed is slow at this frequency. So I guess any good sub that does not add upper harmanics (and then destroy the good quality of the WP7) will do here.
Peter
Peter