If you opt for a Bluetooth speaker with an integrated AUX input, you will benefit from several advantages. Source devices that do not have a Bluetooth function, such as MP3 players or desktop PCs, can be used via an AUX cable, also known as a 3.5 millimeter jack cable. An AUX input can be useful on the go when the speaker's battery charge is running out. Wired signal transmission consumes less power. Because an AUX cable doesn't require power, it extends the speaker's battery life.