Battery not Amp?

Ok now this maybe a stupid or odd question, but I need to know. A few months ago my Kicker amp literally just stopped working out of the blue and wouldnt power back on. So I took it out, because it was useless to me in there. Well I figured I would check the battery and see what the deal is there, but it supposedly was good, everything tested fine. Well about a day later all my electronics started to act up. My dash lights were dimming, the headunit would shut off and turn back on, everytime I would turn the heater on ALL my lights inside and out would go very dim. So I changed my battery because that is the only thing it really could have been, When I change it everything stopped dimming. Now my question is, do you think that my amp is fine and it was really my battery the whole time? Is it possible for the battery to operate the car and not power the amp? I want to ask before I go and drag my sub and amp and everything back out and hook it all up, because right now time is is not something I have.

hook it up and find out.

Ok now this maybe a stupid or odd question, but I need to know. A few months ago my Kicker amp literally just stopped working out of the blue and wouldnt power back on. So I took it out, because it was useless to me in there. Well I figured I would check the battery and see what the deal is there, but it supposedly was good, everything tested fine. Well about a day later all my electronics started to act up. My dash lights were dimming, the headunit would shut off and turn back on, everytime I would turn the heater on ALL my lights inside and out would go very dim. So I changed my battery because that is the only thing it really could have been, When I change it everything stopped dimming. Now my question is, do you think that my amp is fine and it was really my battery the whole time? Is it possible for the battery to operate the car and not power the amp? I want to ask before I go and drag my sub and amp and everything back out and hook it all up, because right now time is is not something I have.

That sounds like the alternator or somthing in the eletrical system of the car.

sounds like a weak or dying alternator

Paul is right about alt.
Since your battery is 12v, you're going to need about 13v to recharge it.
There are some higher line amps that can compensate for lower voltages by drawing more current, but kicker is not one of 'em.
Doublecheck and make sure your alt is putting out 13v-15v 'cause you're going to need that for your trickle charge.
You'll need about 10v to start your car and 11 volts to sustain most 12vdc equipment including car amps.
Also test to make sure none of your positive(+) cables are grounded.