Whys my amp cutting out?

I have a car audio setup in my house. Whenever I turn up the volume on my radio my amp cuts out and makes my sub do a popping noise. I've had a few people on youtube tell me my power supply isnt good enough and I need a car battery to power the amp. I also thought the same thing. My bro on the other hand told me that my power supply pushes a constant 12 volts and there is no voltage drop involved. He told me its probably doing it because my sub is not broke in yet and the amp is trying to push a lot of watts to it and its freaking the amp out making it cut out. Or the amp is just faulty. I dont understand. Can someone please tell me what the real problem is.