Welcome to AVS. Mods ask that you post all questions in the owner's thread in the player. There is no way to revert to a previous version of software. If you are getting stereo, make sure that Secondary audio is turned off. Also make sure the player is set to bitstream. If you run through a receiver, make sure it is set to Amp and not TV (or however your receiver kists it). If all else fails do a reset of the player. That has been known to work.
Please use the report post button to alert staff to problematic posts. Never quote or respond to them yourself.
Oppo UDP-203 -> Yamaha CX-A5100 -> Sony XBR-75X940C; Mediabridge 6' and 15' HDMI cables.