Many guitar players, it seems, believe that their ears are on their ankles — their amps sit on the floor and point straight forward. The problem is that guitar amps are quite directional in their dispersion. If your amp is on the floor pointing forward, then your ears aren’t hearing the actual sound that is coming out. This almost always results in two things:
1. You can’t hear yourself, so you turn up too loud, and kill the audience members directly in front of you.
2. You can’t hear the highs, so you increase the treble, and kill the audience members directly in front of you.