left headphone/speaker output not present after resuming from sleep

I have speakers connected to my MBP 13" (late 2013 model) and I've noticed consistently that they seems lose the LEFT channel sound when resuming from sleep after a period of time. Sadly, I can't seem to find a rhyme or reason to it. However, just as consistently as they don't work after resuming from sleep, if I unplug and then plug the headphone cable back in, music resumes without issue and remains fine until the next time the computer sleeps and the cycle repeats.

The act of unplugging and plugging back in the cable into the headphone port is an unnecessary action and I'm afraid it will premature wear the port. I've attempted to reset the PRAM and NVRAM to no avail. Anyone else have this problem? Or is it possibly a MoBo issue and will getting a replacement solve it?