Ubuntu MATE 16.04 - Sound issues

lshw

        *-multimedia:1
             description: Audio device
             product: 8 Series/C220 Series Chipset High Definition Audio Controller
             vendor: Intel Corporation
             physical id: 1b
             bus info: pci@0000:00:1b.0
             version: 04
             width: 64 bits
             clock: 33MHz
             capabilities: bus_master cap_list
             configuration: driver=snd_hda_intel latency=0
             resources: irq:31 memory:dba30000-dba33fff

syslog

May 18 18:55:08 anomander rtkit-daemon[1902]: Supervising 4 threads of 1 processes of 1 users.
May 18 18:55:08 anomander rtkit-daemon[1902]: Successfully made thread 5987 of process 1901 (n/a) owned by '1000' RT at priority 5.
May 18 18:55:08 anomander rtkit-daemon[1902]: Supervising 5 threads of 1 processes of 1 users.
May 18 18:55:08 anomander rtkit-daemon[1902]: Supervising 4 threads of 1 processes of 1 users.
May 18 18:55:08 anomander rtkit-daemon[1902]: Successfully made thread 5988 of process 1901 (n/a) owned by '1000' RT at priority 5.
May 18 18:55:08 anomander rtkit-daemon[1902]: Supervising 5 threads of 1 processes of 1 users.

Sound dropouts every few seconds, with several lines appearing in the syslog each time. The process mentioned
in the syslog is /usr/bin/pulseaudio --start --log-target=syslog.

The sound hardware is Gigabyte GA-Z87N-WIFI onboard, using coax digital output.

The sound functioned flawlessly in 16.04 Beta 2, but broke after updating to release. It remains broken after doing a clean install.

# cat /proc/asound/cards
 0 [HDMI           ]: HDA-Intel - HDA Intel HDMI
                      HDA Intel HDMI at 0xdba34000 irq 34
 1 [PCH            ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xdba30000 irq 31
 2 [NVidia         ]: HDA-Intel - HDA NVidia
                      HDA NVidia at 0xdb080000 irq 17

# cat /proc/asound/card1/codec#2 | grep Codec
Codec: Realtek ALC892