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While the 55PUS8601's screen specifications and features make impressive reading in most ways, they do raise one concern based on past experience: can the TV's edge LED lighting array deliver the screen's high brightness levels without compromising the image's contrast? Especially as there's no heavy duty local dimming system in play?
Unfortunately the answer is that it can't.
For instance, dark scenes routinely appear on the 55PUS8601 behind a quite noticeable grey 'wash', especially – although not exclusively – if a mostly dark shot contains a bright light or object towards its centre.
Clouded judgement
These sorts of mixed-brightness shots also reveal signs of backlight inconsistency in the form of gentle clouds of extra light in parts of the screen where there shouldn't be any.
You can reduce the greyness issue and, especially, the clouding if you set the Perfect Contrast feature to maximum, reduce the brightness to 49, set the Bright mode to off and set the Contrast Mode to Standard.
However, some of these settings cause problems of their own, such as light instability, and nothing fixes the backlight issues to the point where the set delivers as satisfying a black level performance as some rival TVs in the same price range.
It's important to stress, too, that getting the deepest and most consistent black level performance from the 55PUS8601 means taking quite a lot of brightness out of the picture, which can lead to some subtle detailing getting crushed out of the darkest areas.
HDR could bring trouble
You have to think, too, that when the 55PUS8601 becomes enabled for HDR the last thing you'll want to have to do is remove too much of that 700 nits of brightness. In other words, I can't help but suspect that getting a suitably punchy HDR performance out of the set will mean having to put up with clouding issues and washed-out blacks.
To be fair, this is only speculation on my part, as the HDR firmware update is not yet available to test. Also, I don't think the 55PUS8601 will be by any means the only TV that potentially struggles to control its backlighting effectively when trying to handle HDR.
None of this, however, alters the fact that even with the standard dynamic content I could test, the 55PUS8601's contrast performance was only fair to middling.
In most other respects, thankfully, the 55PUS8601 is more accomplished. Particularly impressive is its sharpness with native 4K content; it does an excellent job of delivering the extra detail and clarity 4K is capable of.
Incredible 4K sharpness
This 4K impact isn't just a result of having so many pixels in the screen, either. The raw resolution is backed up by excellent colour tone subtlety and some exceptionally polished motion handling from the Perfect Pixel Ultra HD engine, which is capable of removing essentially all of the judder and blurring issues LCD screens can suffer when showing motion.
The motion processing can cause some distracting, unwanted side effects if you use it on its highest setting, but even on its low or mid setting it really is effective in making sure motion doesn't spoil the 4K effect.
Colours look bold and punchy despite the impressive amount of tonal subtlety on show (at least if you use the set's occasionally over-enthusiastic Colour Enhancement feature) and the 55PUS8601's screen proves more adept than most at soaking up on-screen reflections too.
Unfortunately we have to finish this section on another negative note, though, as the 55PUS8601 is unexpectedly average at upscaling non-4K sources to the TV's native 4K screen.
Colours look less natural and balanced, and unless you use the Ultra Resolution feature upscaled images look really quite soft; and if you do use the Ultra Resolution feature pictures tend to look a bit noisy and processed.
