Perhaps there actually is one that re-routes 5.1 from an external source besides the built in tuner(s), but I have yet to work with one personally.
I assume you are working with an older receiver that does not have HDMI and wish to send along sound from your blu ray player(?) At some point the ARC standard added onto HDMI might help-
Hi. I'm looking for an HDTV with 5.1 audio output. Only few HDTV have it. My Panasonic LCD only output 2.1, samsumg's only output 5.1 from turner, but not from hdmi connections :S. Is there any TV with full 5.1 audio output?? (sorry for my poor English)