There were two refurbs up for a smacking price this morning, I trust you snagged one of those, nice one!Managed to get one from the Panasonic Outlet (Ebay) today - woohoo
Any setup tips etc? Must own 4k disks?
Is it recommended to run dual HDMI outputs (AMP / TV) or single?
I am not aware of a difference or benefit for running a separate HDMI for audio and did not notice a difference when I tried it with my Sony X700 - but this was not for the purposes of listening based audio tests.
Make sure you first set the Panny to the display luminance setting which matches your display. I would advise leaving any post processing settings such as edge sharpening at zero if you want to preserve the image as close as to mastered and intended.
My current personal main 4K UHD reference/ test discs are Blade Runner 2049, Blade Runner (1983), Mad Max: Fury Road, Avengers Infinity War/ Endgame and Planet Earth II. But you will find that 2049 and Fury Road are cited as reference, along with ones like Sicario and I think Planet Earth II.
Some of my favourite experiences thus far in terms of image and audio have been all of the above, as well as Dawn of the Planet of the Apes, Baby Driver, Hacksaw Ridge, Logan, Deadpool 1 and 2, Avengers Infinity War and Endgame, The Lion King, and most recently Escape from New York and Predator (1987). There are a lot of 4k UHDs out there now - have fun!