Yes, 3.5 mono jack cable, Marantz out to Rotel in - that's it. As soon as Marantz gives 12V at its trigger out, Rotel will power on.
It seems working good. The power amp can be turned on and off with the receiver.
One question, the power amp should be always in power-on state, I shouldnot power off the amp completely. is this right?
That's right, it stays in "standby" mode when off (no 12V at its trigger input).
Normally, power consumption is rather low in standby, so nothing to worry about.
Most likely, you switch off your receiver with the IR remote - in this case it's also in standby, waiting for your "on" signal from the remote.
I have 12V trigger out,but no trigger in on the amp. Is there a simple circuit I can build to make a 12V trigger in?