When the worlds of high-definition home-theatre systems and portable electronics collide, the result is the sobering reality of technical obsolescence. The new Onkyo TX-SR875 audio-video surround-sound receiver illustrates that point. It offers a host of features I didn't even know I needed and renders the top-of-the-line stereo receiver I bought three years ago outdated. AV receivers are one of many components typically found in a home-theatre system. Their main purpose is to amplify sound from a variety of audio sources and route video signals to a television from various sources, including DVD and multimedia players. Planet of sound The TX-SR875 has the THX stamp of approval. THX is the trade name of a high-fidelity sound reproduction system developed by American inventor Tomlinson Holman at Lucasfilm, the California-based studio of Star Wars filmmaker George Lucas. Being THX-certified means the Onkyo receiver follows the THX perform-ance standards for sound quality, usability and interoperability. It also includes a number of proprietary THX technologies designed to compensate for the acoustical errors that occur when movies and music are translated from the professional studio to the home environment. Feature comforts The TX-SR875 is one of the first receivers on the market to feature Neural-THX Surround decoding, which allows content to be transmitted in a two-channel format and later decoded for up to seven discrete audio channels - at 140 watts per channel. It supports DTS-HD, Dolby Digital Plus and Dolby TrueHD to ensure you're getting the most from your HD DVD collection. It can also handle older surround-sound technologies and has a microphone for auto-speaker calibration. One vision On the video side, the receiver supports the all-digital High-Definition Multimedia Interface standard with four HDMI 1.3 ports. This interface replaces analogue standards, such as coaxial cable, video graphics array and the older digital visual interface. The TX-SR875 is also one of the first receiver models to include Silicon Optix's Reon-VX HQV video-processing chip. This technology provides the receiver with video scaling and de-interlacing capabil-ities, which means converting your low-resolution 480p videos to the high-definition video mode 1080p. As such, the receiver also has three sets of component video inputs and six inputs for S-Video and composite video. The TX-SR875 is priced at HK$11,800. A slightly scaled-down version, the TX-SR805 (three HDMI ports and 130 watts per channel), costs about HK$3,000 less.