I've recently purchased a new #RokuUltra and Amazon Fire TV+, and am using them on an also-new very high-end television. I often use them both simultaneously on different HDMI inputs, so the differences were very easy to point out.
I've noticed three key differences:
1) Most annoying, the picture on the Roku--on multiple streaming channels--drops momentarily intermittenly. Meaning the screen goes black for anywhere between 1-4 seconds, then resumes with live television.
2) After a few minutes, the screen brightness slowly dims from normal to a significantly lower setting. This happens gradually over the course of five seconds, and it stays there. If I go back to the Roku home screen, it readjusts but then repeats this issue once I've settled on something to watch.
3) The sound quality is frankly horrible. The bass blares through, often making dialogue extremely difficult to understand.
There are no differences in the TV settings from one input to the other. I have checked.
I am no stranger to Roku. I've been using numerous Roku products for 5-6 years and have never encountered any of these issues.
I can return this Roku device (purchased from Amazon) through January 31st, so I have some time. But obviously I want to figure this out as soon as I can. Any suggestions?
Update: I've upgraded my HDMI cord, which seems to have taken care of the temporary blackout issue. But the fade and sound issues still persist.
After consulting an expert at Best Buy, it appears that even the Roku Ultra just isn't built to handle extremely high-end televisions... at least not yet. Which is a shame because I like Roku's UI far more than Amazon Fire TV's, and I've got no interest in an Apple TV for the price.
I'll be returning this Roku device, and still using the 4K Roku stick in my bedroom TV.