The MX650 must not have sold as well as Sanyo's other models, because it doesn't appear as frequently on Ebay. It has a very unique appearance, with a single massive grill covering all of its speakers. But wait, Sanyo cut a hole in the middle of the grill to make room for a special control panel which includes the mic mixing input and the AMSS track search feature. Some collectors have removed the grill and painted the plastic around the speakers to create a custom look.
I haven't seen a service manual for this model, so I don't know its exact specifications. But I'm guessing it's from 1982 or 1983.
Model versions for different countries include the M-X650K and M-X650LU.
