This should probably be asked in the chromecast thread or display thread. I am not familiar with the chromecast, but if there is a Dolby Vision setting, disable it as Samsung displays do not support Dolby Vision.
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Panasonic DP-UB820 -> Yamaha CX-A5100 -> Sony XBR-75X940C; Mediabridge 6' and 15' HDMI cables.