DVDs and digital music sources hold a huge amount of audio data, including a considerable amount in the low frequency range. Multi-channel sound formats dedicate an entire channel to the low frequencies (the ".1" in 5.1-channel sound), used to deliver the bass in music and explosions, thunder and other low frequency sound effects in movies. Ordinary speakers are not large and robust enough to handle these frequencies, especially for long periods. This is where the subwoofer comes in. By outputting bass sounds with high power and low distortion, it ensures that you are not missing anything, and it also makes the overall sound richer and properly balanced. A subwoofer is thus a vital part of any home theater or even music-focused system.