What should I do with my sound system?

I have a new battery running at 14v, a stock 1992 75 amp alternator, and I am running a Pioneer 480 watt amp pushing a 12 in. dual voice coil kicker cvr. BUT my battery is being drained by this I've already replaced one battery. What should I do? From what I read a Cap wont help much for such a small system. Should I install another battery just for the amp?