If your LG soundbar is 2.1 channel (most are), you would only be getting a psuedo surround effect. Sometimes a bitstream input to the soundbar will give it more to work with, sometimes not. If you can resolve the difference in sound from either digital or analog to an LG soundbar, you should classify yourself as a Golden Ear. I have listened both ways on more than a dozen different soundbars that have passed through my home (too many of the came to live) and don't believe that I can tell a difference. Still like to use optical just because I think it may be better. My wife has better ears than I and she can hear no difference. As info, she always wins.
Also, one of the first things I usually do is turn off psuedo surround modes from most soundbars as the out of phase and delayed sound muddy what I think I should be hearing.