Head over to the MUG (Magnepan Owners Group) site, and/or Planar Speaker Asylum. The main failing in old Magneplanars is of the glue Magnepan used to attach the conductive wire onto the Mylar drivers (it was ultraviolet light and moisture sensitive. They switched to a different glue about 15 years ago). When that happens, the end loops of the wire come loose and make a buzzing or rattling sound. Play some music with heavy bass and turn the volume way up to see if your pair need to be reglued. If they need no repair, the IIB is worth about $300/pr. If they need repair, they are worth basically nothing (unless you repair them. Instructions and glue are available from Magnepan).
