Joe,
I ran into a similar problem a few weeks back when I first recieved my 4806. This is where I ran into the terminology of "down-conversion" which, of course Denon doesn't do.
If I understand your setup correctly, all of your connections are by component jacks except to the plasma which is by s-video connection, am I correct? If so, to go from component to s-vid would be considered a down-conversion and therefore not compatible. If it were the other way around, it would work... it did for me. I'm not sure if the cat5 cable modulator has any effect but I suppose it is possible.
I have an older Sony TV that the most effient connection option was s-vid. Since my DVD player and 4806 had component cable connections in common, why not go with the most efficient option and use the component cable, at least for those two units right? Nope, because there was a down-conversion in the formula (component to s-vid), it wouldn't work. When I replaced the component cables with s-vid so they were all on a equal plane, it all came together.
I hope this helps, you are looking in the right place for your assistance (on the Home Theater category)... many people came to my rescue with much appreciated advice.
Good Luck,
Bud
