7 Channel A/V Receiver with Auto MCACC and USB Host (Black) Amplified and optimised AV precision in your home The 817 includes our unique MCACC system, which stands for Multi-Channel Acoustic Calibration. At the touch of a button, the MCACC will optimally tune the amplifier to the size of your living room space and speaker placement. The result sounds like a professional recording engineer has fine-tuned your system. Greater flexibility in your speaker placement By simply placing your speakers directly beside your TV screen and activating the unique Front Stage Surround Advance feature, you can experience a virtual surround sound environment. The benefit here is that you don?t have to worry about routing speaker cables around your room; your speakers can be placed up front. Crystal audio; even from compressed files The 817 includes a USB host on the front which means you can access compressed audio files. And with our unique Sound Retriever technology (which up-converts compressed audio to CD-quality audio), you are guaranteed high-quality sound. This receiver is also available in Silver.