Original post by: Nick Nishino ,
Sounds like your battery is bad, alternator not charging, upgrade battery to higher capacity or run additional auxiliary battery. Are you running the speakers at 2ohms this wiring configuration will demand more power to drive the amps. Confirm your amp power cable size 4awg or larger is good add AUDIO CAPACITORS 1farad or higher rating to your amps should prevent headlights from flickering. Have your battery tested under load, confirm your alternator is charging your battery properly. Check all ground wires to your amps. Bad ground will reduce power to your amps. If all else fails have a reliable audio shop look at your setup.