Do you have a DVD player with component outputs, and is that (presumably) working correctly? If your older SA 8000 worked with the 950 and if a DVD player works, there has to be something on the output of the 8300 that is causing the problem, not something in the 950. I suppose it's too obvious to ask if the Y/Pr/Pb cables are connected correctly? (Easy and understandable thing that has happened to more than one person here!)

The 950 doesn't feed anything back to the box, as you suggest, but the box can impose some sort of copy protection on the output, and that may be the cause.