How to choose the best car amplifier for your car?

A complete buying guide 
When you come up with a decision to upgrade your car audio system, installing an amplifier is essential. You may face the confusion related to buying an amplifier for your car or not, but if you want the music listening experience to be loud, then amplifiers are essential in a car audio system. A car amplifier brings liveliness and life into the music played in a car. A car amplifier system comes with a number of advantages. Some of them are listed as follows: 
● Better Sound Quality: Installing an amplifier definitely increases the quality of sound inside a car. This is because an external power amplifier is not restrained to the space available. Unlike the amplifier inbuilt in the default audio system, an external amplifier can be designed and installed without any compromise with the quality of sound. This means that the speaker can produce great sound because of a clean power source, ensuring a cleaner, detailed and louder sound at all levels of volume. 
● Extra power for upgraded car speakers: The pre-installed receiver inside a car will not be able to provide adequate power to the upgraded car speaker package without an external amplifier. If you are looking to top up your car music experience using an aftermarket speaker or component system for your car, you will require more power for peak performance than pre-installed receivers can provide. This makes external car amplifiers a viable bet for an upgrade. 
● High-power for a subwoofer: Subwoofers in a car audio system require much more power than factory-fitted receiver inside a car can provide. So, an external amplifier is a must, in the case of a subwoofer installation. 
Enhancing the power of a pre-installed car audio system 
The preinstalled car stereos are usually made to offer about 10 watts RMS maximum output power per channels. This power is not enough to reduce the on-road noise and offer best sound experience. To upgrade the car audio system without spoiling the factory interiors, one can choose to upgrade the factory system with external amplifier and sound processing gears. These systems are custom-designed for a vehicle to ensure improved sound quality and stock interiors. 
If one looks forward to upgrading the sound system economically while trying to not hamper with factory installations, one can choose to get hold of compact 4-channel amplifier. The four channel amplifier boosts the power of front and rear speakers. These amplifiers are equipped o handle high-level signals from a car’s factory speaker wiring. While choosing an amplifier to add to preinstalled speakers, look for an amplifier with support for ‘speaker-level inputs’
Ensuring the best output from aftermarket speakers & component speakers
Aftermarket and component speakers require more power than a factory or aftermarket receiver can provide. It is essential to check the Continuous RMS power ratings while choosing a speaker. A higher RMS rating, usually in a range of 5-60 watts RMS power range, represents the approx. driving power for a speaker at which it will produce the loudest and best sound. In reality, the speakers can take much more power than rated for (approximately 150% more power than rating is safe). But to ensure the best output from speakers, it is essential to get at least 75% of the power rating from a receiver. External amplifiers help in achieving the fete and enhancing the music experience. 
In case your car is adorned with aftermath speakers, you need to find out the top RMS ratings for the same. If you have two different pair ratings for front and rear speaker pairs, keep in mind the lower ratings for choosing an external amplifier. Multiply the rating from 0.75 to get the minimum RMS wattage per channel an amplifier must have for you to choose the same. To get the maximum output per channel you want from the amplifier, multiply the RMS rating of your existing speakers from 1.5. If you are unable to find a small amplifier to match low-power rating speakers, set the amplifier’s gain to a low level. This will ensure that amplifier does not get full power and promise safety of your installed speakers. 
If you are a person who does not use rear speakers and use only front speakers for music, a 2-channel amplifier will be the best bet as you will only need to power single pair of speakers. But in case you need to fill your rear speakers with full power and need front-to-rear fade control, you should buy a 4-channel amplifier. 
If you are looking to include a subwoofer in the car audio system, then you must take care of other amplifier configurations. A 3-channel amplifier can handle single pair speakers and sub woofer effectively, whereas a 4-channel amplifier can run a pair of speakers and a sub woofer while giving an option to expand your system. In the future you can change the settings to run 4 speakers and can add separate amplifier for the subwoofer. 
A 5-channel amplifier can power up the whole system in a single package while larger amplifiers with more channels are designed to run 3 and 4 way active systems with one amplifier channel dedicated to a single driver like a tweeter, midrange speaker or subwoofer. 
Getting new speakers with a new amplifier 
If you are building a car audio system from scratch, you must be clear in mind about how loud you want it to be. It is essential to choose the best components for the system. You must know that car audio system does not necessarily need massive power because car audio systems can sound loud without them too. But you must have adequate power to deliver powerful sound with the demands of a music number. Also consider the interiors and size of your car to determine the amount of power and sound you need inside a car. 
An amplifier with 50 watts RMS per channel or smaller will be the best for blocking road noises and ensuring clarity in music inside a compact coupe, hatchback or a sports car. Choose a speaker with top RMS rating of at least 35 watts RMS to go along with the same, following the 75/150 percent rule. 
If you drive large vehicles or want more loudness, you can go with an amplifier with at least 75 watts RMS per channel. It is essential that speakers with top RMS rating of 50 watts RMS are chosen to match a speaker with the amplifier. You can go for a system with 100 watts RMS per channel or more if you want your music to be real loud and impactful, with each speaker having 75 watts RMS rating. 
In case you want to just add a subwoofer
Subwoofer amplifiers are essential to amplify bass in a sound system. There are many kinds of amplifiers designed for subwoofers like mono, 1-channel which work with a range of impedances and have tone controls and filters that are ideal in reproducing bass. Although, many two and four channel amps can be bridged to increase power and run a subwoofer, but not many amplifiers can handle low impendence of a subwoofer. This leads to over heating or an amplifier going into protect mode. Also, bass should be musically blended and well balanced with the system for best sound quality. So, before choosing a subwoofer amplifier, you must make sure of the following: 
● In case of a preinstalled factory studio in a car, 50-200 watts RMS power for a subwoofer to reproduce bass will be the best. 
● With an aftermarket receiver, 200-300 watts RMS power for sub is the best
● Amplified speakers having capacity of 50 watts RMS per channel must be complemented with 250-500 watts RMS for bass. 
● With a system with 100-watts RMS or higher per channel, at least 1000 watts RMS for sub is required
Impedance match must be conducted between a subwoofer’s amplifier and a subwoofer for the best results failing which will either lead to issues like low impedance to run and overheating among others. In case of adding subwoofer to a factory system, a subwoofer amplifier with speaker level inputs will be the best as it can get signals from factory speaker wires.