[OtinG]

I have made some discoveries for getting Prime Video 4K to properly stream on my Fire TV Cube 2nd generation device.

In order to get Prime Video 4K to stream I had to use Settings —> Display and Sounds —> Display —> Video Resolution —> 2160p 60Hz.

Using the Auto (up to 4K Ultra HD) option doesn’t seem to work for playing Prime Video 4K with the Fire TV Cube. I’m not sure why, but with my setup it didn’t work. After changing this setting to 2160p 60Hz I was able to stream previously purchased video content in 4K. If you are not in the USA you might need to use 2160p 50Hz instead.

Additionally, I recommend using Settings —> Display and Sounds —> Display —> Color Depth —> Up to 10 bits if your TV supports 10 bits color depth.

Additionally, I recommend using Settings —> Display and Sounds —> Display —> Dynamic Range Settings —> Always HDR if your TV has HDR capability. Using the Adaptive option doesn’t seem to work for playing Prime Video 4K with HDR on the Fire TV Cube. I’m not sure why, but with my setup HDR didn’t work with the Adaptive option.

The Cube seems to require some fiddling around to get it to stream 4K and 4K HDR correctly. I assume Amazon needs to debug the firmware. The TV 4K doesn’t seem to have these kinds of issues.