Hi;
Well I've looked and don't see a cover but the investigation will continue.  There are two sockets, one for the microphone and the other for the control head.  To the right is an rs232 connection
Below the microphone jack and control head jack are two sockets which I guessed would be for a key and amplifier.  Might have to do the unthinkable and look at the manual.
The fact that the designers of this box totally changed the plug's that kenwood used for years might be my only complaint but once that's worked out we should be set to go.  My next project is to come up with a cable for the amplifier.  It uses the same type of pin plug's found on most stereos so I'm hoping I can easily find one premaid.
Richard