Machine

There have been many bands that have pushed the boundaries of what we consider to be music, and many people have also put music into a box of what it can and cannot be. So my question to you fellow music lovers is where is the line drawn? When do we say music has to stop evolving? And just what defines something that is indeed pushing the boundaries. Is music all forms of audio, or does it go farther, or in fact are these types of audio-stimuli but into boxes that may not be broken?