Applying the fix at https://wiki.ubuntu.com/Audio/InstallingLinuxAlsaDriverModules did fix my problem; but I needed to reboot to make the change take effect.
I updated that wiki page to make it more obvious that a reboot is required when using the command line install instructions. ** Changed in: alsa-driver (Ubuntu) Status: New => Fix Committed -- [Realtek ID 270] ALSA test tone not correctly played back https://bugs.launchpad.net/bugs/663866 You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs