The transformer doesn't specify a volt rating. It looks like an unbranded one.
It is a 2.1 speaker system and i had been using it for more than 2 years. A few months ago, the transformer died and i had it replaced. But i knew something was wrong. The room would smell of burning wires just after 10min of use. I opened it and noticed the transformer was getting hot. Last night, i had it running for 3 hours when the music stopped. I looked down and i noticed fumes were coming out of the woofer vent. I opened it and found the transformer had melted away. The metal thing around it had swelled and popped out of place. The circuit has no burn parts. Just a few wires seem to have melted and the cushion inside the box had burned.
The output wire from the transformer has a socket which goes into the circuit. It looks like the one you get on a 12v chassis fan.