Not sure if I need a new battery or alternator or becasue maybe my amp loses power when it heats up but when I firs turn my system on in the morning it's loud and clear but aftr a few minutes the bass isn't as precise and loud. I'm pretty confident it's not my alternator becasue I've had the car run at night with no system on and then I'll blast a bass tone at say 40 hz and my lights don't dim. My car has a 140 amp alt and I'm running a 400 wat profile amp. It's a mono sub amp wired to 2 ohms. But maybe it's my battery? I'm not to sure.
well alts dont last forever so it could be on its way out. I would bet more on your amp heating up and components not working as well due to heat though.
You could have a voltage drop from your battery to your amp..
But normally when your situation happens the amp is going into protection ( assuming the amp has it)
Just try playing it loud while near the amp and see if it gets hot. If not you either have a bad amp or electrical system.
And while you are out trying to figure out whats wrong get one of those$15 yellow multimeters they are best friends to all those who work with electronics