Yay!  OK, finally got it to work.   Instead of uninstalling the driver from the Device Manager, I uninstalled it from "Programs and Features" from the control panel. So, this is the process that I used to get it to work Go to "Control Panel" => "Programs (uninstall a program)".  Find the Realtek Audio Driver in the list, right click, uninstall.  Reboot the device. Once rebooted, go to [URL] and search for the correct device (in my instance, Inspiron 7490) and click on the "Drivers and Downloads tab".  Search for "Realtek High Definition Audio Driver" and download. Once downloaded install and follow the prompts to install.  Make sure you reboot when you are done This really is much harder than it should or needs to be.  I am convinced that the issue with my original laptop is pretty much the same, but Dell support went the hardware route.  At least they sent me a replacement after my original one had been disassembled twice.
OK, this is getting a bit silly. I have just received a replacement Inspiron 7490.  This replacement laptop was sent because I couldn't get an external microphone to work when plugged into the 3.5mm jack and after Dell replaced both the daughter and mother board on the original one. Out of the box, it all worked fine.  Now, after updating using both Windows update and Dell update, I am getting the infamous MaxxAudioPro error "audio driver is not up to date" and am no longer getting the plugged in device pop up that allows me to choose "headset". Can anyone tell me EXACTLY how to fix this issue? Thanks
MaxxAudioPro "audio driver is not up to date" and no device pop up - Inspirion 
7490