Has anyone had success using this port? Let's say you have a 522 for Sat programming, but kept your cable service as well. You have two sat feed lines, and a seperate cable for the cable service. You hook the cable line to the TV Antenna/ Cable In port on the rec. If you used RCA cables for your input to the TV. How do you switch between Sat and cable? How would this work if instead of the cable service, it was the mirrored signal from a 510? Thanks.