Can an iMac's logic board/motherboard cause audio issues that only occur through devices (e.g. headphones, speakers) plugged into the headphone jack?

For any device that I plug into the headphone jack of my 27in, mid-2011 iMac, the sound cuts out at indeterminate times during the day. This problem can last for half a second at a time, or last as long as 10 minutes before letting up and then just happening again later - meaning 5 minutes later or an hour later. The uncertainty is a nightmare.

First off, there is nothing wrong with the devices that I am plugging into the headphone jack. I have tested them on other iMacs and my Macbook Pro. I have listened, using these devices, for hours on these other computers without any cutting out issues.

Also, the internal speakers of my iMac 27in are perfectly fine. It is really just sound coming through the headphone jack.

My iMac has been restored to it's original "out-of-the-box" state, and the problem has persisted. This leads technicians to believe that it is not a software issue, and must be a hardware issue.

My iMac's internal speakers and headphone jack have been replaced, and the problem has persisted.

There was some belief that it could be an environmental issue. I have plugged my iMac into several different outputs around my house, which are on different circuits. This doesn't seem like it would be an environmental issue anyway, because an issue like that would effect more than just the sound.

It is not a bluetooth issue. The sound has been cutting out even with the bluetooth off, and while using a wired keyboard and mouse.

So, can an iMac's logic board/motherboard cause audio issues that only occur through devices (e.g. headphones, speakers) plugged into the headphone jack?

And, if not, what is causing these audio issues?