SP Layout does not work on 709

Why does the SP Layout always say unavailable? I would like to turn off my rear speakers occasionaly.

Hi dowop,
This can happen when the “Speakers Type(Front)” setting is set to “Bi-Amp”
or if “Powered Zone 2” is set to “Yes”, then this setting cannot be selected. Also if you have selected a Listening Mode which doesn’t support front high, front wide or surround back speakers this setting can also not be selected. One final thing Playback conditions may be limited depending on the settings in “Speaker Settings” and “Speaker Configuration”. Thank you for contacting Product Support via our new forum!