More tinkering suggests this is related to the DisplayPort output on the board. If I disconnect the DisplayPort cable the noise goes away. I am no longer sure that this is a regression since the old Ubuntu version.
** Summary changed: - Noise and poor audio quality over SPDIF (regression since 14.X LTS) + Noise and poor audio quality over SPDIF -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1655429 Title: Noise and poor audio quality over SPDIF To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/alsa-driver/+bug/1655429/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
