I agree with the HDMI to TV link from DVD. Also placing a pair of ICs from the cable box or DVD (or both) to the preamp is the ticket. Audio Art, and Voodoo Cables make some nice inexpensive interconnects that do a great job. Naturally, more $$$ will get you more there too.
it's redundant to run ICs from the TV back to the preamp... unless you are running an outside antenna setup, and quality will suffer.