Most likely released sometime in 1996~
Content adapted from: Kenwood Product Page Spec Page Feature Page Feature Table Contemporary Unit Comparison Chart minkara.carview blog
The optical block may not be very reliable:
“The MD receiver M505, which I have been using for a long time, has reached the end of its fourth pick-up LD. Although it depends on the usage environment and frequency of use, the pickup was hit or miss at first, and it was better if it lasted for about a year.” http://wrx.fc2web.com/kenwood2.htm