Dear All, I bought a pair of AR98ls yesterday. They are really sound great! But I am now confused why my AR98ls' look differrent from the one shown in AR Library: http://www.classicspeakerpages.net/library...series_brochur/ whereby the front face is black colour. Is that my ARs' have already modified by the previous owner(s)? What is the function of the small knob situated above the speaker socket (please see the attached picture)? Can anyone suggest me how to restore the dented midran