Ah , yes . The amplifier will of course put out a more powerful audio signal than it takes in , since that ' s its job . But it ' s not for free that 1000 W or whatever it actually is is going to come straight from the power supply battery for a car stereo , or mains for a home system . The total output will always be less than the total input power , because some of it will be lost to heat and other inefficiencies . That ' s why your headlights might dim when the bass hits the amplifier is drawing so much current that it causes the system voltage to drop . That ' s why many automotive audiophiles will upgrade their alternator , battery cables , etc . or even add capacitors to the system to deal with spikes in demand .