CentOS - Aug 2016 - Sound failure in CentOS 6.8

Sound stopped working on my CentOS 6.8 system several months ago. I've tried
everything I can to find out what's wrong. It is not the hardware; if I boot
into a live dvd of 6.8 (or any other OS), the sound works perfectly. So 
something must have changed in my configuration.

I've compared files on my system and another CentOS 6.8 system with working 
sound and I haven't found any differences relating to sound configuration.

I've scoured the web for help, and found a few sites where people reported
the
same problem, but none of their "solutions" work. Many refer to
sndconfig and
system-config-soundcard which don't exit in 6.8.

I've spent countless hours looking through alsa (and other) documentation
for
any hints that might help. Nothing.

If I crank up the volume on the speakers, and set kmixer to max, I hear a low 
level of white noise coming from the speakers. This noise does not occur when 
I first boot up, but kicks in somewhere during the boot process, I'm
guessing
when the system is attempting to initialize the sound card.

The only substantial info I have about the failure is the output from 
KInfoCenter -> Sound:

--------------
Sound Driver:3.8.1a-980706 (ALSA v1.0.24 emulation code)
Kernel: Linux 2.6.32-642.3.1.el6.x86_64 #1 SMP Tue Jul 12 18:30:56 UTC 2016 
x86_64

Config options: 0

Installed drivers:
Type 10: ALSA emulation

Card config:
HDA Intel PCH at 0xfbff8000 irq 33
HDA NVidia at 0xfaffc000 irq 17

Audio devices: NOT ENABLED IN CONFIG

Synth devices: NOT ENABLED IN CONFIG

Midi devices: NOT ENABLED IN CONFIG

Timers:
31:system timer

Mixers: NOT ENABLED IN CONFIG
---------------

I have no idea what "CONFIG" it's referring to.

A gigantic "thank you" to anyone who can help resolve this problem.

Jeff

On Sun, 21 Aug 2016 13:39:29 -0700
j_post wrote:
> Sound stopped working on my CentOS 6.8 system several months ago. 
alsamixer may tell you something useful.

-- 
MELVILLE THEATRE ~ Real D 3D Digital Cinema ~ www.melvilletheatre.com

On Sunday 21 August 2016 13:50:25 Frank Cox wrote:
> On Sun, 21 Aug 2016 13:39:29 -0700
> 
> j_post wrote:
> > Sound stopped working on my CentOS 6.8 system several months ago.
> 
> alsamixer may tell you something useful.
> 
When I select HDA Intel PCH, which is what it should be using, everything 
looks normal with one possible exception. There are three volume sliders 
labeled  S/PDIF and the second one has "Default" tacked on to it. All
three
have volume set at zero and alsamixer won't allow any change.

The default should be HDA Intel PCH.

I have a strong suspicion that there's a config file somewhere that somehow
got
messed up, but all the config files that I'm aware of that might have
anything
to do with sound match those on a machine with working sound.

Jeff