Re: Surround Sound Echo Problem
It sounds like a delay issue for the TV. Many TVs these days will have a delay built into their audio to allow for the processing delay for the video. So if the audio of your sound system is ahead of the center channel, that's what I would suspect. Many receivers will have a delay you can set in to compensate for this, but if you are using the center channel output of your receiver it would already be delayed and not help. My JVC has a small delay for each channel to compensate for the left and right channels being closer or farther from the center channel, but it is only a few ms. My daughter has one of those new Sharp 4 color jobs and it takes a 200 ms delay to get lip sync due to the TV's processing delay.
I don't know what to suggest for your case other than add a center channel speaker. I don't know of any receiver that has settable left and right channel delay separate from the center channel that would work for your application.
Not sure why not on the BD player and only on cable though.