The DTV setting is confusing me. Should I select this for a 480p source like say a prog-scan DVD player or game system, or is it solely for a DTV reciever? Isn't 480p a DTV signal? In trying both I really can't tell. When I select DTV the image is much brighter so I bring down the brightness and I think it looks better than if I left it at DVD but I'm not sure.. Help!