Help With Setting Up My New TV/Player

[Nice Guy Eddie]

I just got a 75" Samsung MU8000 and a Sony UBP-X800 and I have a few questions about setting it up. I have a Yamaha RX-V377 and I'm wondering if I would be better off splitting the audio/video and running the 4K player directly to the TV (my Sony player has that capability) for a better picture? I did some checking and from what I've read my receiver may not support HDMI 2.0 pass through (I'm not totally sure WTF that even means) but it sounds like a true 4K video signal wouldn't be compatible. I'm much more concerned with the video, if the audio remains the same (even if not true HD I'd be OK with it). I'm also wondering if I truly need one of the new HDMI 2.0 cables or is that just a load of bull. Currently I've got the 4K player run into the receiver and the receiver to the Samsung 'One Connect'. It looks fantastic the way it is but I'm not truly sure if it's working 100% properly. When I got the new player hooked up yesterday I tossed my Wonder Woman 4K disc in and a blue warning screen came up saying something along the lines of 'be sure to get full 4k by connecting this player to a 4K TV'. This is the only 4k disc I have at the moment so I wasn't sure if this is some generic thing that's on all 4K discs since the format is so new or if it was something specific to my set-up because I'm not truly getting a 4K signal.