First problem: My TV doesn't have a plain line-level audio output! It has a headphone jack and a coaxial S/PDIF output.
Funny thing is that it actually does have a line-level audio out. When I took more pictures to add to this blog post I noticed it, but I swear it wasn't there before!
Even without one it's not a huge problem. This little box does the trick. It's a S/PDIF to unbalanced audio (RCA) converter. It works with both optical and coaxial S/PDIF in, and I already had one I use on another TV using optical S/PDIF and it worked great there. The S/PDIF coaxial connection is the blue cable, above.
So now I have a regular unbalanced line-level RCA phone plug signal - how do I get it to the opposite side of the room?
All of my wiring uses the Leviton QuickPort wall jacks. Browsing the catalog of devices, I found these nifty devices: They're audio over unshielded twisted pair. The picture is from amazon.com, as I forgot to take a picture before I installed it.
Basically with one 4-pair cat. 5 cable you can run a stereo audio connection. Perfect! I fished the wire, ran it through the basement, and switched the existing plates to ones with 2 more holes.
At the other end, theoretically I would have just run the audio into my mixer and be done with it. Unfortunately, I get an awful hum, and it seems to be the TV's fault - there's no hum until I make the last coaxial S/PDIF connection.
Fortunately, this little box, a Behringer hum eliminator, came to the rescue and it worked perfectly! The photo is from samedaymusic.com, which is also where I got it from. I uses unbalanced 1/4" mono TR plugs, but so does my mixer, so that worked out okay.
And that did it! It sounds much better than my TV's built-in speakers.