The number of channels in an audio setup denotes how many speakers the sound outputs through. Common configurations include 2.1, 5.1, and 7.1 channel systems. Systems with 5.1 or 7.1 channels offer an immersive surround sound experience.The first number represents the quantity of speakers used, with 2 speakers in a 2.1 channel setup. The decimal indicates the presence of a subwoofer, with 1 denoting its inclusion, as in the case of 2.1 channel sound. This structure allows for a diverse range of audio setups tailored to different preferences and environments.