I bought a KVM switch with keyboard and mouse and audio cable capability earlier, and just recently tried to use it. I got it out of the box, all the cables I needed plugged in, then looked at it and realized it wasn't going to work. I don't know what these people were thinking when they designed it, there's no fucking way it could possibly work as a KVM switch. For one thing, there is no power source. Secondly, the only connections to the computer from the KVM switch are the audio cables. The thing takes USB keyboard and mouse, but there's no way to actually get the data from there to the computer. The only other connection to computer is for the monitor, which I don't actually need.
Well, I tried it anyway, thinking maybe the KVM switch, despite having no power source, would somehow communicate with the computer through the sound port. (Especially since the audio ports go from USB to audio, oddly.) It didn't work.