When I first got my HDTV, I used a CableCard and the built-in tuner on the TV. My TV, a Hitachi RP LC 55" display, has a Toslink digital audio output. I connected that output to a Toslink input on my pre/pro, and voila! I got full Dolby Digital input from the TV signal.
If your TV doesn't have a Toslink or RCA digital output, you can use the analog stereo output from the TV, plug it into your pre/pro, and then use an analog surround matrix program in your pre/pro (e.g., Dolby ProLogic or DTS Neo) to give you 5.1 channel.
Do you use a separate cable tuner box? I recently switched from direct-tune w/CableCard to a cable box. Its outputs include composite video, component video, HDMI, RCA and Toslink digital audio outputs, and 2-channel analog audio. I connect the cable box to the TV with an HDMI cable, and then I connect the cable box's RCA digital output to an RCA digital input on my pre/pro. Or I could just as easily use the Toslink.
In fact, I've also connected an analog stereo pair of interconnects from the cable box to my pre/pro because sometimes the stereo downmix from the cable broadcast is better than the Dolby Digital feed, and my pre/pro can make a better surround matrix from the 2-channel analog feed.
If your TV doesn't have a Toslink or RCA digital output, you can use the analog stereo output from the TV, plug it into your pre/pro, and then use an analog surround matrix program in your pre/pro (e.g., Dolby ProLogic or DTS Neo) to give you 5.1 channel.
Do you use a separate cable tuner box? I recently switched from direct-tune w/CableCard to a cable box. Its outputs include composite video, component video, HDMI, RCA and Toslink digital audio outputs, and 2-channel analog audio. I connect the cable box to the TV with an HDMI cable, and then I connect the cable box's RCA digital output to an RCA digital input on my pre/pro. Or I could just as easily use the Toslink.
In fact, I've also connected an analog stereo pair of interconnects from the cable box to my pre/pro because sometimes the stereo downmix from the cable broadcast is better than the Dolby Digital feed, and my pre/pro can make a better surround matrix from the 2-channel analog feed.