if the head unit has mp3 support sir then the campaign track on repeat should be ok as source.
during the 2010 elections I installed two kinds of setups. 1, using all 12V amps and 2, used an AC inverter to provide power for those who already have their amps. iirc, I used a 1kva AC inverter similar to those used in solar power systems.
ang nakikita ko sir ngayon puro naka inverter na and using those sakura/konzert videoke amps from Raon.
hth and good luck po sa inyong bayaw.