I had an older Vizio tv and got a sound bar and sound was in sync. When I got a new 50 inch Vizio a few months back, my sound was out of sync. In both cases, I had the hdmi from the hopper to the tv and then to the sound bar. When I had trouble with the new Vizio, I also tried using optical from the tv to the sound bar, but it still was off. My tv allows for syncing the sound (perhaps your's does also), but instead of "slowing it down" to match the video, it could only be moved the other way because it was at its "slowest' point by default.
I fixed it by running the hdmi from the H3 to the sound bar and then an hdmi from the sound bar to the tv. It is fine now.