Surround Sound Echo Problem
I am an AV professional, and have run across a problem that has me and everyone I know stumped, maybe one of you may be able to shed a light on the issue. I just installed a NEW 3-D home theater system. Samsung 8000, Onkyo NR808, and a 3-D BD player. The issue we have is the is a echo between the L, C, R speakers when viewing Cable (Scientific Atlantic DVR) and not with the other sources. Now our configuration is a little un-conventional; but we have used it with great success in the past. The entire 5.1 system is connected to speakers with the exception of the center channel. We are using the center pre out in order to use the TV as the center speaker. While viewing any other source the sound is perfect. But Cable gets a very annoying echo. I am also unable to remove speech from the L & R speakers using any of the speaker configurations. The only difference between now and previous setups is the equipment. The HDMI/DVI RCA audio in has been merged with the PC 3.5 audio in by the manufacturer, and the system is a part of the new internet based receivers and TV's.
Any thoughts would be appreciated.
I must add if your idea is connection related or configuration related realize I am very experienced, and an actual AV engineer so beginner problems are not a consideration, and as I said before this configuration has worked well before. I am looking for in-depth help, not... "Did you try a fiber optic cable?"