Yo Tobi or not Tobi?
If you check your MD=8 manual, pages 13/and/14, the TR IN rca jacks are "used to connect the OUTPUTS of a stereo master recorder to the MD8. The master recorder could be a DAT deck, minidisc deck or a cassette tape deck. Connect them to your master recorder's sstereo outputs. To monitor the output of the stereo master recorder during the mixdown, press the 2TR IN MONITOR SELECT switch."
I've never used these INS but I'm guessing that you would take something from a DAT and put it onto a disc in the MD8.
Since the STEREO outs of the MD8 can be used to record the final mix FROM THE MD8 TO whatever, then it seems the the 2TR IN plugs would be RECEIVING a signal that would be recorded by the MD8.
If I'm wrong, Nilbog the Goblin will correct me.
Green Hornet