Made the jump to 4K yesterday and it is glorious!
We must have details!
Railton
Just set up the X900E tv and STR-DN1080 avr yesterday. We are still in a condo while we look for a house so just went with a 2.1 setup using my old speakers for now. It is plenty for the small space. We are sitting about 10-11' away from the 65" screen. Watched natgeo 4k videos off youtube. I was embarrassed by how engrossed I was watching a damn cheetah run in slow motion.
Had to upgrade my Netflix membership to access the Ultra HD and HDR content. Watched a few scenes from Daredevil, and then watched Sunday Night Football. NFL was obviously not in 4K.
The Sony does a great job "upscaling" the 1080 content to 4K, looks excellent. The blacks are very deep. If all the lights are turned off, and the TV screen goes black, there is no glow whatsoever. I cannot even see the remote in my hand in front of my face.
Tonight I'll do some calibrating on the AVR, and see what the PS3 games look like on the TV. Have about 4 games to beat before I pick up the PS4 at black friday!