The Bluetooth Adapter needs a 5V supply. The amp uses a 12V supply but I suspected there was a 5V line in there somewhere. I removed the four corner screws, pulled out the circuit board, powered it up, and probed around until I found a 5V supply. Next, a hole was drilled in the amplifier's PCB and metal housing, the Bluetooth adapters power connector was trimmed, and the wires were soldered up and fished through the PCB/housing. This step can be skipped if Bluetooth functionality is not desired. To run the amp off of an audio cable, I close the enclosure with only one latch and route the audio cable through the other side with the unlocked latch. This closes the enclosure but does not pinch the cable.

The amp was reassembled and mounted into the enclosure along with the speakers. I soldered up a power adapter using a X60 connector and a barrel plug I had one hand. If a power adapter connector is not available, a cable like this 2.1mmx5.5mm splitter would be suitable. The battery was connected to the Amplifier, the Bluetooth Adapter was connected to the Amplifier input and power cord, and the two speakers were wired up.

This thing is surprisingly loud for its size and each battery lasts around 4 hours at high volume. The treble and bass adjustments on the front make it easy to tune and the mini remote is pretty handy as well.