Sony has announced the Bravia X900A 4K Ultra HD TV. Launching in the spring, it will be Sony's flagship 4K set and features all the bells and whistles you would expect.This means a 4K picture with the X-Reality Pro picture engine keeping things ticking over. On top of that, there is the Motionflow XR 960 engine ensuring you get a super-smooth image. Rather predictably, when putting out 4K images the set looks stunning. Colours are incredibly vibrant and motion silky smooth.\u00a0The problem is that there isn't that much 4K content to view on the screen. Sony is instead going big on upscaling 1080p to 4K. We saw a Blu-ray upscaled on the set and it looked great.\u00a0The display itself is "Triluminous'" or essentially massively bright, detailed and colourful.\u00a0Sony is also launching the world's first 4K video distribution service to go along with the TVs, further bulking out content.The set of speakers on either side of the display make for an unusual-looking design. They pack quite a stereo punch as demoed to us and boast proper diverse and rich audio that outdoes what you would normally hear from a TV.The whole set is passive 3D and will come with four pairs of glasses in the box. There is also built-in Wi-Fi, ticking the Smart TV box, as well as access of course to the Sony Entertainment Network. Sony's Smart TV experience is looking good as ever and at 4K its even nicer.That built in Wi-Fi can also be used for screen mirroring or alternatively MHL can be used. Then there is USB playback, completing a fairly robust feature set.\u00a0Also thrown in with the TV is an NFC remote.\u00a0As for screen sizes, this will start 55 inches and go up to 65 inches. With 4K and passive 3D, expect this one to be a looker. You just need to find the 4K content to watch on it.