I have a 1000 watt amp (300 watt rms) connected to 2 10in subs, and it worked fine on my old car battery (which was already about 6-10 years old) for about 4 months. I bought a new battery, and a month later the battery is getting low on power (headlights fading, headunit switching off, battery not starting for a while after turn off). Is it the sound system thats causing problems or did I just get a bad battery? (Everlast or whatever they sell at Wal-mart)

Best guess-you have an alternator thats going bad,
or the alt. belt is loose and slipping,which should cause a loud sqeeling noise,which you may not hear over your sound system. Headlites dimming,etc. indicates a low voltage condition.
Hope this helps.

Yes!! I do hear the sqealing noise, its been going on for a while. I guess ill take it to a mechanic to get the belt replaced/tightened. Thanks.