Hi John.
The pre-out on the NAD receiver is for connecting an external amp.
The main-in is for conecting an external source that has its own volume control. Like, some CD players have a volume control.
Unless your receiver has a pass-through where the signal from another receiver (connected to the main-ins) bypasses the preamp section of the NAD and will drive the NAD's amps directly, I would not recommend doing this. I seriously doubt your NAD has this. In fact, I've never heard of it, but that does not mean it ain't out there somewheres.
Most modern receivers are designed to give the option to use the preamp section only and drive external amps. They are not designed to have an external reciever drive their internal amps.
My suggestion is to buy an external amp(s) for the new receiver.
The pre-out on the NAD receiver is for connecting an external amp.
The main-in is for conecting an external source that has its own volume control. Like, some CD players have a volume control.
Unless your receiver has a pass-through where the signal from another receiver (connected to the main-ins) bypasses the preamp section of the NAD and will drive the NAD's amps directly, I would not recommend doing this. I seriously doubt your NAD has this. In fact, I've never heard of it, but that does not mean it ain't out there somewheres.
Most modern receivers are designed to give the option to use the preamp section only and drive external amps. They are not designed to have an external reciever drive their internal amps.
My suggestion is to buy an external amp(s) for the new receiver.