Additional testing shows the problem isn't with the audio output per se - I bypassed Pulse completely and the problem persisted. It turns out nVidia broke SPDIF passthrough to HDMI in their more recent drivers. I've raised the issue with them.
Additional testing shows the problem isn't with the audio output per se - I bypassed Pulse completely and the problem persisted. It turns out nVidia broke SPDIF passthrough to HDMI in their more recent drivers. I've raised the issue with them.