I currently have Direct TV hooked up to my TV. I want to add a Sony Blu-ray BD/DVD home theater System Model # BDV-T10/T11/E300.
Can anyone help with cable set-up?

I can. Give me the model of your TV and your DirecTV box.

Also, could you be more clear about which BD surround sound it is? You just listed three models. It should say on the front of the head unit itself. It should be on the top right-hand edge or on the front bottom right corner. I'm guessing you got that model from the owner's manual which is printed for each of those models.

Most likely here is what you will need:

HDMI cable from Blu-ray player to TV.
HDMI cable from DirecTV box to TV.
RCA cable from DirecTV box to "SAT/CBL" connection on Blu-ray player (will probably be colored orange, and it doesn't matter what RCA cable you use).

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You should also check the settings on the Blu-ray player and DirecTV box. If you give me the models I can give you specific directions on how to do this also. But basically make sure the resolution settings match your TV's and that the DirecTV box has Dolby Digital audio enabled (by default it is turned off). If this isn't setup, then you'll not be getting the best picture and sound quality... even if you use the right cables.