...When playing either a 4k disc or a Blu-Ray I get frequent but random snapping sounds mostly from the center speaker. The volume of the snaps is about the same as what normally comes from the speakers. The picture is unaffected but the snapping makes movies unwatchable...
Is the loudness of the snapping effected by volume level? Check to see if it's just the center channel.
Are you doing any upmixing? Is the material Dolby TrueHD? or DTS-HD Master Audio?
I haven't had this experience with my Oppo-203.