MX-122 hook up

[ChicagoDog]

I'm sorry for all the questions. It must seem to you guys like I've been "hooking up" stuff forever and I have due to time constraints. I have tested my 501's and MX-122 in 2 channel mode. That's it. Tonight, I've started to clean up and hook up behind the cabinet. I want to get my video sources (and their associated audio) figured out. I have an 82" 4K Samsung display and it has a single proprietary cord that attaches to the display at one end and a small box on the other. The small box has 3 hdmi inputs and the 4th is labeled hdmi arc. it also has 1 optical output. My sources are Amazon 4K fire Tv (only has 1 hdmi output) a DirecTv box (not 4k capable, only has 1 hdmi output and 1 optical output) and a dvd transport (only has 1 single hdmi output, nothing else) So, in order to have 5.1 (and above) sound I need to get the MX-122 doing its magic. So...plug all my sources directly into corresponding labeled hdmi inputs on the back of the MX-12 right? Figure out the settings by playing in each devices various menus right? But, I was thinking...maybe I want it set up so that sometimes the wife and kids can just turn on the tv and the Amazon fire and/or the Direc tv box without the need for all my McIntosh stuff turned on (audio through tv speakers only, no Mc gear on) SO...if I run all my hdmi sources into that box and a arc from that box into the MX-122 and a single optical out from that box into the MX-122 I'd not be taking the fullest advantage of the MX-122 capabilities right? BUT I would be able to have "all Mc" when I want and also wife/kid friendly at times too?? If given only 1 choice I want to get the best possible picture and sound regardless. How.