hi, i have the newest 27" imac. the imac is connected with the original apple usb-c to hdmi adapter with my av-receiver, and from the receiver to my tv with another hdmi cable. when the tv and the av-receiver are both off, not stand-by, the imac still sees the av-receiver. i dont want that because now the mouse is not stopping at the edges and i always have to switch between internal and external speakers. anyone have a solution for that?