If you add the Amazon Echo Sub Bluetooth Speaker, you will create a fascinating audio atmosphere. It delivers down-firing and provides a deep bass sound that adds punch to the Echo Smart Speaker when you play music on it. It will enhance your audio experience. You can play music, make calls, set alarms, check weather and news, control smart home devices, order food, book a cab and a lot more using the Amazon Echo Sub devices. You can also pair it with the Amazon Echo Plus to get that refined and impactful sound.