Well, I'm happy to report back that with the help and direction of all who steered me here, I have it nailed!
That external sound card I posted above just arrived a few hours ago, and I got it hooked up and running.
I found out after buying it that it's an old device, made when Win XP was going strong. I had to download the latest drivers from their website to get it to work with Win 10, plus it took some fiddling in the settings, but I have it figured out now.
Works like a champ, and I have awesome surround sound in my office now! :)
Wish I could wind it up to really try it out, but with a neighbor on each side I have to be polite.... :B
Thanks everyone for your input. :)
