This is the Blu-ray player I have:
http://www.samsung.com/uk/audio-video/blu-ray-player-f7500/
For blue ray I just use one cable leaving the blu ray player, to the reciver, to the TV. I don't have the 4K upscaling on the blu ray player turned on, I let the TV sort it out.
These are the specs I pulled out of Sony's manual for the TV:
Video (2D): 4096 × 2160p (60 Hz)*, 4096 × 2160p (24 Hz), 3840 × 2160p (60 Hz)*,
3840 × 2160p (24, 25, 30 Hz),1080p (30, 60 Hz), 1080/24p, 1080i (60 Hz),
720p (30, 60 Hz), 720/24p, 480p, 480i, PC Formats
* YCbCr 4:2:0 / 8 bit
Video (3D):
Frame Packing 1080p (30 Hz), 1080/24p, 1080i (60 Hz), 720p (30, 60 Hz), 720/24p
Side-by-Side 1080p (60 Hz), 1080/24p, 1080i (60 Hz), 720p (60 Hz)
Over-Under 1080p (30, 60 Hz), 1080/24p, 1080i (60 Hz), 720p (60 Hz)
Audio: 5.1 channel linear PCM: 32, 44.1 and 48
I have one apple TV 3 in another room. The TV has apps built in, but I really hate the UI of it, and having the apple TV tied into everything else is nice. So, I already splurged on the ATV4K unit. I don't have an issue of upgrading my receiver. I can see where it will be more beneficial with the apple TV to do so, but not sure if I can gain anything from the blu ray. If that's the case, a cheaper solution would be to just plug the apple TV into the TV HDMI port and let ARC return the audio, but I don't want to do that if all I am going to get is 2 channel stereo. I don't mind if it's not in Atmos HEOS super dolby 14.1.3.4.21 surround, but 5.1 would be nice. Also, all I need is one more reason to justify a new receiver. Lol.