It's a strange thing to say that a major highlight on one of the first 55-inch Ultra HD TVs is, in fact, sound quality. But that's exactly what the KD-55X9005A excels at, along with searing amounts of 4K detail and a fine upscaled Blu-ray experience.
Aside from detail, the KD-55X9005A does brilliantly with colour - and even better with sound.
In fact, we'd rate it as the best-sounding TV around. The design is high-end, the user interface slick and the 4K detail stunning. More importantly, at least at this early stage of 4K evolution, is upscaling, and some good news; Blu-rays have never looked better - and that goes for 3D as well as 2D discs.
If most Full HD TVs are best fed an HD-only diet, that goes quadruple for the KD-55X9005A, which doesn't make as much of the 4K detail as its bigger 65-inch sibling.
Active vs passive 3D
Standard definition sources look rather ropey, and we also noticed some issues with contrast and the 4K-cancelling amounts of motion blur.
We're also not convinced that built-in speakers - and the consequent super-wide design - will appeal to the kind of home cinema aficionados that are bound to be most interested in the KD-55X9005A. At 34.5kg it's a whopper, but is it really big enough to show-off 4K?
With only slightly less wow factor than its big sibling, the far pricier KD-65X9005A, the KD-55X9005A is currently the best value Ultra HD telly around.
But it's not just the pin-sharp performance with (as yet non-existent) 4K sources that blew us away. As if to throw the AV world a few crumbs as we await 4K Blu-ray, Sony's provision of some awesome speakers flanking the 4K panel are a timely reminder of just how much cinematic impact is from sound.
Colour, too, is stunning, and the upscaling of Blu-ray is proficient.
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The downsides are a touch of motion blur and the somewhat ropey-look to upscaled standard definition sources, where the maths involved proves too much.
One of the best performers with Blu-ray, let alone 4K, the KD-55X9005A is a standout winner with 3D, too. The passive 3D system's loss of resolution here looks less like a compromise, and it's always smooth and bright. Until we wait for native 4K Blu-ray discs to drip onto the market, the KD-55X9005A has plenty to keep anyone satisfied.
Also offering 55-inch-or-thereabouts Ultra HDTVs is LG, Samsung and Toshiba.
If you want to save a few quid, head for Toshiba's slightly larger 58-inch 58L9363DB (£2,999).
Both Samsung and Toshiba use the Active Shutter 3D system on their Ultra HDTVs. Most are available in 65-inch versions, too, but the prices almost double.