Newer Yamahas do not turn on with Input commands. However, if your model allows for scene commands, you can setup a scene in the receiver to power on and set all the properties. Then you just need to find the Scene commands in the MX450 and add just the scene command to your macros to power on, set inputs, set sound field. You could either setup a Scene for power off or call up a Scene with power on and then send the power toggle command.

Sorry, I don't know if your model supports scenes.