Looking at the signal flow in the receiver, the signal comes in from the source, goes out the tape output, and then back into the tape input. There's no way you can reverse that signal flow.
If I follow correctly, Tape would not be selected as the source in the instance you outline. In that situation, I have no reason to disbelieve what you are saying (though it does raise the question of whether you could monitor a 3 head tape machine on modern equipment).
I did not mean to imply that any signal flows got reversed.
It is that the Tape output gets shut off when you select Tape for the source.
I also tried the same thing with the CD/R input and output with the same result.
It seems that Marantz decided it was a good idea to disable the outputs for whatever Source is currently selected.
I input from my CD player and "pass" the signal to my 2nd receiver.
If I connect the CD to the CD/R inputs and select CD/R as Source, I cannot output via the CD/R output terminals.
If I connect the CD to the Tape inputs and select Tape as Source, I cannot output via the Tape output terminals.
As long as I output from different terminals than what is selected for the source, I have output.
I assume Marantz's logic is if you are listening to your Tape deck, there is no reason to send an output signal to your tape deck (and the same for CD/R).
I find this a little curious as it
seems like a little extra effort to selectively disable outputs and I wonder what the intended benefit might be.