Unknown & Interesting to watch ...

The first 'dead giveaway' is if the 12V side of the transformer was actually AT 12 volts (~50Hz)
the little 4ohm speaker in parallel would 'go nuts' and burn out with smoke 😉
The very clever deception is the filaments of the bulbs actually flicker > as if on a generator.
 
More on the SONY SS-CS5 cheap speakers.
When available at $100 a pair > I would love to hear 6 pairs set-up as a STEREO 'wall of sound' costing only $600 !!!
With a little extra internal damping installed, just imagine the Headroom for SPL and power handling. It could be impressive ???