CNET writes much about 4K. In fact, a lowly 720p plasma was really good at standing up to 4K.
Here's the links.
Check that chart about distance to a 55 inch set to see all 4K glory. Also, many 4K sets are still only 30Hz or have less than the latest HDMI standard. And the new HDMI HDCP can cause trouble with older gear.
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Between Sony KDL55W800B and Sony XBR55X800B , which one has the overall better picture quality and can bring about better experience watching 1080P movies and blue rays? Is the screen on XBR55X800B superior to, or at least on par with KDL55W800B on other aspects besides resolution?
I can get both the XBR55X800B and the KDL55W800B for a fair price and I am in a dilemma whether or not to go 4K right now... If you've had experience with one of them, please help.