Many auto amps are made for competition.... In the competition world, they have power classes. Those classes are normally based on how much total power you have in your vehicle based on a 4 ohm power ratings on your amplifier. However, many of these amplifiers are rated at how much power output that they are capable of at 1 ohm or even 1/2 ohm with all channels driven... A few of the excellent competition amps will double their output down to 1/4 ohm load..
So, 100 watt per channel amp @ 4 ohms gives you a 3200 watt amp @ 1/4 ohms …. again, "all channels driven"
So, 100 watt per channel amp @ 4 ohms gives you a 3200 watt amp @ 1/4 ohms …. again, "all channels driven"