Some more observations. I have a Gigabyte GA-EP35-DS4 v.2.1 mobo. With this dump patched in, my "Internal Speakers" play by default, and I can switch to "Line Out," which works just as well. These constitute the green and black mini-plugs on the back of the board, respectively. At least now I have four usable output channels.

I at least get an input level on the pink "Internal Microphone" plug, but it's nothing useful - just noise. This may be due to the mic I'm using.

All of this is more than I had before.