I am reaching out for a help to diagnose and to fix the problem I am having on my Ubuntu box.
The OS: Linux 3.16.0-51-generic #69~14.04.1-Ubuntu x86_64 GNU/Linux Desktop with default Unity Desktop environment.
Faulty hardware ruled out. The sound out of the Headphones Jack worked with no issue before updating from Ubuntu 14.04 to Ubuntu 14.04.1 via apt-get dist-upgrade.
The Issue: When headphones are connected to a headphones jack, sounds comes out distorted, seems like in a mono (once channel) When that takes place, channel balance controls (L-R) are inaccessible in control panel.
All applications producing the sounds affected in the same way.
When headphones removed from a headphone jack, sounds returns to build-in internal speakers of the laptop with no issues (normal sounding stereo). HDMI connected external monitor/TV producing sounds just as expected with no issues.
This bug seems to be isolated just to headphone jack handling by OS.
If anyone knows the solution to resolve this FOR SURE, please share.
Thank you for your time.