HT-BD8200 Sound Bar Audio Sync Issue
If it gets progressively worse, it may be an issue with the player or the disc. This symptom could be common in discs that contain files that were downloaded and burned, but if you're using regular pressed store-bought movies or rentals, then it may be an issue with the player.
You noted the sweet spot in your post in reference to the smaller increments. Did you find a setting that "almost worked", say between 55 and 60? Or were all of the settings getting further from synchronization?
Let me know and I'll look into this further.