[MS-7968, Realtek ALC1150, Black SPDIF Out, Rear] Underruns, dropouts or crackling sound. Test tones work but sound immediatly returns to poor quality after completion.

Using digital audio output on Intel driver.
Sound from games is barely decipherable over the distortion/crackle. Playing test tones (left/right test and on bug report) work fine but the noise returns when the clips are completed.

Tried tsched=0, hda fix 1 and hda fix 2. no luck yet
When first added tsched command, it blurs the screen and no audio devices are available. remove, restart, re-add and screen and audio back but problem still present (maybe just spelt wrong first time?).

Help appreciated.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: alsa-base 1.0.25+dfsg-0ubuntu5
ProcVersionSignature: Ubuntu 4.4.0-38.57-generic 4.4.19
Uname: Linux 4.4.0-38-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
AudioDevicesInUse:
 USER PID ACCESS COMMAND
 /dev/snd/controlC1: nytonial 1759 F.... pulseaudio
 /dev/snd/controlC0: nytonial 1759 F.... pulseaudio
CurrentDesktop: Unity
Date: Sun Sep 25 15:28:53 2016
InstallationDate: Installed on 2016-09-07 (17 days ago)
InstallationMedia: Ubuntu 15.10 "Wily Werewolf" - Release amd64 (20151021)
PackageArchitecture: all
SourcePackage: alsa-driver
Symptom: audio
Symptom_AlsaPlaybackTest: ALSA playback test through plughw:PCH successful
Symptom_Card: Built-in Audio - HDA Intel PCH
Symptom_Jack: Black SPDIF Out, Rear
Symptom_PulsePlaybackTest: PulseAudio playback test successful
Symptom_Type: Underruns, dropouts, or "crackling" sound
Title: [MS-7968, Realtek ALC1150, Black SPDIF Out, Rear] Underruns, dropouts or crackling sound
UpgradeStatus: Upgraded to xenial on 2016-09-08 (16 days ago)
dmi.bios.date: 02/23/2016
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 1.60
dmi.board.asset.tag: Default string
dmi.board.name: Z170A XPOWER GAMING TITANIUM EDITION(MS-7968)
dmi.board.vendor: MSI
dmi.board.version: 3.0
dmi.chassis.asset.tag: Default string
dmi.chassis.type: 3
dmi.chassis.vendor: MSI
dmi.chassis.version: 3.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr1.60:bd02/23/2016:svnMSI:pnMS-7968:pvr3.0:rvnMSI:rnZ170AXPOWERGAMINGTITANIUMEDITION(MS-7968):rvr3.0:cvnMSI:ct3:cvr3.0:
dmi.product.name: MS-7968
dmi.product.version: 3.0
dmi.sys.vendor: MSI
modified.conffile..etc.modprobe.d.alsa-base.conf: [modified]
mtime.conffile..etc.modprobe.d.alsa-base.conf: 2016-09-25T14:21:58.691691