What are the technical specifications (i.e., Power, Impedance, Frequency Response and Sensitivity) of Two (2) black Saxx&Vadar Floor-standing Sub-Woofers, the dimensions of which are 110x25x20 cm and three (3) of the speakers are 18cm in diameter, and one(1) is four (4) cm? the front and rear panels are flat and the two side panels ccurve to the rear panel which is 12 cm across. \nThough they are likely 20 ++ years old, they still rock the building at about half strength!! \nWhat is their likely value in USD or Sterling? All help gratefully received.