Somewhere in my attic is a Recoton stereo adaptor that they sold over 10 years ago. It was about half the size of a VCR and had a small, wired stick-on probe (coil ?) that you attached to any of the audio coils. It picked off the stereo and the box decoded it and gave line level outputs for a stereo.
It had Dolby NR, synthetic stereo and a few other features.
It worked great, but I gave up on it when VHS' got cheap and cable came to my neighborhood. I went to that method. My CTC9 is delivering fine surround sound today.
Here is one on ebay right now.
http://cgi.ebay.com/ws/eBayISAPI.dll...category=14978