Here are a few things to know when buying a new amp.
How to tell if I am getting a good amp?Shop for reputable brands. Look at the size, weight of the amp. Look at the fuses that are either plugged into the amp, or specified by the instruction book. If you see a 400w amplifier with a 5-amp fuse, you should be suspicious.
What Else to Look For in an Amplifier
It is a good idea to get an amp with a built-in crossovers. If you are going to be using multiple speakers, make sure the amp is 2-ohm stable. A bridgeable amplifier could come in handy in the future if you are planning to upgrade. Overheat, short-circuit, overload protections are good features that any good amplifier should have.
The more power you get, the cleaner the signal going into the speakers. A common misconception is that if a 100-watt amplifier is used on 50-watt speakers, the speakers will burn. More power is always better. For systems with a lot of power, you might also have to upgrade the car's electrical system, by getting a high output alternator, capacitors, etc.
