Microsoft's Director of Product Planning Albert Penello detailed the temporary limitation in a post at NeoGAF. "For the Dolby only headsets, my understanding is that these will work but you will only get stereo audio since we only pass Stereo and DTS through the optical port," Penello wrote. "I have not tested this myself, but I'm told it works. Regardless, I understand this is an inconvenience, but again we're going to have Dolby coming."
Penello also addressed speculation regarding the console's rumored inability to produce HDMI-IN surround sound output at launch, explaining that players will need to opt in to beta surround sound support via the Xbox One's TV Settings menu. Otherwise, HDMI-IN audio is converted to stereo output by default. Penello notes: "We found some inconsistencies in [set top boxes] during testing and decided to disable it by default to insure a good initial setup experience for people."