Originally Posted by
DrNomis_44
Headroom is basically a measure of how much an audio signal can increase by until it gets clipped, the greater the headroom, the more a signal can increase before the onset of clipping distortion.
What you want to do is make sure your audio signal level is high enough so it doesn't get buried in hiss and hum-noise, but not so high that the signal-peaks start to get clipped, best way to achieve that is to set the gain control so that the loudest peaks in the audio just get to 0dB, or maybe -1dB, once it is set about there then your signal levels should be about optimal.