I'm not sure if this is a "buy a box" issue, a "buy a better cable" issue, or "you're SOL". I have a desktop computer with a couple of audio input jacks (a mic jack and a line-in jack; nothing special ...
In an effort to record system audio on a laptop with no system output in my Recording Control, I decided to try plugging a short male-male mini cable from my headphone output to my mic input.