I found a pair of stereo speakers that come with an amplifier inside them.
They do run on mains voltage as they plug into the wall but the actual amplifier runs on DC, 12V to be precise. There is even an unused port that says 12V DC, presumably for a wall adapter. The first component in the circuit of those speakers is a center-tapped transformer that steps down the mains voltage to 12V (still ac). The outputs of the transformer are two 12V AC wires that directly connect to the full wave rectifier on the amp board and one center tap for getting the ground potential (hence the two 12V wires). In the end, the main audio controller and amplifier chips run on 12V DC.
Can you run this amplifier from a DC source, like a battery, if we ignore the transformer and directly connect it to the board?
I am asking this because I am planning on building a portable speaker with the components of these speakers.