I'm recording music with Audacity, and I've noticed that whenever I record a track, the sound from the other tracks (that I playback while recording) is recorded too. It's not loud, but loud enough to be a problem. In fact, this happens not only in Audacity; any program that records input also grabs whatever sound is output, could be from VLC or anything. Lowering the output volume helps, but I have to keep it so low that I can barely hear the music I'm playing to.
It seems that the only thing that really affects the level is the level of what I actually hear in my headphones, I can find no way around it. I've played around with all of the sliders available in the ALSA mixer, with no effect. Switching "mic jack mode" does nothing. It's not just my headphones leaking (I thought so at first), because even with just a dead cable in the output jack, it does the same thing.
What's up with this? Where does the problem lie?