I have recently added digital cable to my A/V setup. They offer 5.1 Dolby Digital on certain HBO and PPV movies, but my Sony receiver only has 1 coaxial input, which is being used by my DVD player. Is there such thing as a converter or adapter, so I can connect the Coaxial Digital Audio out to the Optical Digital Audio in on my receiver? If so, where can I find one? Thanks, Mike S.