Sound problem w/ cable TV/home theater speakers

Does it look like this:

The amazon page says it does have an optical input. (Digital audio input: 2 (optical)). If his TV has one that probably is the best solution. I would bet that the Audio Return Channel is likely the cause of his issues, and more importantly its cheap to try it ($2 + shipping for a 6ft optical at monoprice:

If you do that, you would turn ARC off on your TV, setup your TV to turn the optical output on and internal speakers off (if needed, some are just always on). Then you would turn the input on the blu-ray player/receiver to optical in when watching cable tv. If you don’t have an optical out on your TV but do have RCAs (Red/White), run an RCA cable to the miniplug input and use an RCA->miniplug adapter (
But if at all possible use optical inputs.

Edit I see I missed your last post, if its working for you, great. If you ever want to hook up say, an Xbox or Wii or something it might work better if you use optical out on the TV if you have it. (ie sound + video to TV, sound -> bluray/speakers).

On the cable box, Optical always equals audio, plus if you have red/white RCAs, which you almost certainly do, those are audio out too. (on the picture above those are above the L AUDIO R labels - but on most devices they are colored white and red)

I think this is what I have set up already: cable–>HDMI–>TV, then TV–>HDMI & optical–>Blu-Ray

So should I change the connection from TV–>optical–>Blu-ray to cable box–>optical–>Blu-ray, or does it matter?

No, if you are going HDMI to your TV and then optical to your blu-ray you are digital all the way and should be good. You avoid lipsync problems too by going to the TV first (the sound being ahead of the pictures - which you can get if you connect cable box-> bluray and your TV has a large amount of what is called “input lag”)