One way of streaming music from a cell phone to loudspeakers is by using a Bluetooth amplifier. These units have Bluetooth reception as well as amplification built into a single unit which is usually quite small. However, one of the drawbacks of using such an integrated device is that the wattage is usually quite limited. This limitation stems from the fact that most of these Bluetooth receivers work with a fairly low supply voltage such as 12 V. As a result, when connecting speakers with an impedance of more than 4 ohms, the wattage is usually quite low because the voltage swing can be generated by the receiver is not sufficient to drive speakers loud enough.

Let me show you some ways for improving loudness in those cases. Obviously, the simplest solution is to purchase speakers that have a low …