[H55M-D2H, Realtek ALC887, Green Line Out, Rear] Underruns, dropouts or crackling sound

[Maceatron]

crackling and noisy audio out of only LH speaker. Only recently started on upgrade to 16.04. Previous versions worked correctly with no changes.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: pulseaudio 1:8.0-0ubuntu3
ProcVersionSignature: Ubuntu 4.4.0-21.37-generic 4.4.6
Uname: Linux 4.4.0-21-generic i686
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2
Architecture: i386
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: tron 1912 F.... pulseaudio
 /dev/snd/controlC0: tron 1912 F.... pulseaudio
CurrentDesktop: Unity
Date: Fri Apr 29 07:17:59 2016
InstallationDate: Installed on 2016-04-24 (4 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release i386 (20160420.1)
SourcePackage: pulseaudio
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:MID successful
Symptom_Card: Built-in Audio - HDA Intel MID
Symptom_Jack: Green Line Out, Rear
Symptom_PulsePlaybackTest: PulseAudio playback test failed
Symptom_Type: Underruns, dropouts, or "crackling" sound
Title: [H55M-D2H, Realtek ALC887, Green Line Out, Rear] Underruns, dropouts or crackling sound
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 05/04/2010
dmi.bios.vendor: Award Software International, Inc.
dmi.bios.version: F1
dmi.board.name: H55M-D2H
dmi.board.vendor: Gigabyte Technology Co., Ltd.
dmi.board.version: x.x
dmi.chassis.type: 3
dmi.chassis.vendor: Gigabyte Technology Co., Ltd.
dmi.modalias: dmi:bvnAwardSoftwareInternational,Inc.:bvrF1:bd05/04/2010:svnGigabyteTechnologyCo.,Ltd.:pnH55M-D2H:pvr:rvnGigabyteTechnologyCo.,Ltd.:rnH55M-D2H:rvrx.x:cvnGigabyteTechnologyCo.,Ltd.:ct3:cvr:
dmi.product.name: H55M-D2H
dmi.sys.vendor: Gigabyte Technology Co., Ltd.