Seeing some of the info posted after you, it seems likely that my DTV box was upgrading the SD video when I had it directly connected (via HDMI) to my TV. I've not gone back to fiddle with the DTV settings to force it to send 480i... call it my "I'm still really happy I got everything working again" attitude problem.
In my mind, if the DTV is upgrading the SD already, why doe the "HDMI VIDEO DIRECT" (I'm going to start referring to this as the HVD function) block it in the first place? Is the DTV querying the 5308 for a native resolution and the HVD function then kicks in and shuts it down? I don't know, that logic doesn't track either. Does the HDMI communicate that its sending an upgraded SD signal and that triggers the HVD function to block it? Why would anybody want that?
This does make some sense because I'm confident my blu-ray player is not upgrading my SD (DVD) picture and it comes thru with HVD enabled just fine. It must have something to do with the games that the DTV box is playing with the signal.
If the DTV is upgrading the video, that means my 5308's video chips are not doing the job I thought they were. I wonder if I should go into the DTV and fiddle with the settings, but that could get confusing because I think it asks for what the TV is capable of, not what you want to be sent.
Anybody have any idea what DTV boxes are using for upgrading video? Software, hardware? How would it compare to the 5308's Realta chips? I'm not expecting an answer to that, I doubt that's easy info to come across. This is an interesting question regarding picture quality from DTV. It may be that DTV really locks us out of our picture quality and I had thought my 5308 was helping, at least with the SD stuff.