Smart Theatre Systems Center Surround CS-3X Processor for Digital Surround EX Decoding.
5.1 audio source is encoded down to two channels, then re-decoded back into 5.1 channels and redistributed back to the 5 speakers (front left, center, front right, left surround, right surround, plus the subwoofer) in such a way as to create a more immersive sound without losing the directionality of the original 5.1 channel source material. Also, Circle Surround can also expand two channel source material into a full 5.1 channel surround sound listening experience.