Hello fellow 990 owner (Version 1 UD5).
I would like to follow your thread and see the responses as well. A few years ago I purchased a Klipsch ProMedia 4.1 setup, which worked well with previous cards, but not so much anymore. It utilizes the two center ports of the onboard audio. It has two front, two rear and a subwoofer that I would stand up against nearly anything. Unfortunately, with the current incarnation, I have to set it for 7.1 to activate the rear channel. The sub simply follows the fronts.
Previous incarnations of Realtek allowed for adjustments to the speaker settings (distance adjustment) and environment (basement, auditorium, etc), but the current one does not. Maybe somewhere down the road.
A while back I was contemplating the same thing as you, and I may do so again in the future, but I see little for good quality sound at the local MicroCenter. I will be watching this thread. Good luck!