Well, Radio Shack called what I was thinking of a "demodulator," so I went with that. All anyone seems to have now is an RF Modulator, which takes audio/composite video and/or audio/S-video as an input and outputs to audio/composite or audio/S or coax. Of course Radio Shack also sold me the box I threw away last year, even though he claimed they "never made those."
What I'm looking for is a box that gives me coax (cable signal) in, with outputs for stereo audio, composite video and coax, all of them live. My old Radio Shack box also had an S-video out in the mix.
As mentioned in my original post, I *do* realize that I would have to use the coaxial out to plug into the TV so that I could use the TV's tuner, then keep the TV on mute and pass the sound into my stereo receiver. Just tryin' to get better sound to go with the cheapo TV in my home office
There literally is not space for a VCR, which I know would accomplish this.
So ... it looks like this kind of device is not in the cards -- and the TV sound in my office will be tinny ...
BTW, thanks Mark for answering on both forums -- I thought there would be different members on the two different sites' discussions but obviously I'm not the only member of both