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From reading your owners manual, it's not clear to me. My guess is that it is outputting 2-channel PCM, and that could give you matrixed surround sound (such as Dolby Pro-Logic), but not Dolby Digital 5.1 surround. The best way to answer that is to give it a try.
Does your cable box have a digital audio output, or any other audio outputs? If you can connect a digital audio output from the cable box directly to the receiver, then you could get the full surround sound that way while still watching the program on your TV.