How to Choose a Car Head Unit

The head unit is the control center for your car sound system. Often referred to as a car radio (because most of them include a radio), this single component can have a huge impact on how good your system sounds, the way your dash looks, and how easy a time you have doing things like switching inputs while driving.

Choosing a head unit can be daunting. They are often expensive, and selecting the wrong one can poorly affect how the system sounds. If this is an upgrade you're interested in, but you aren't sure where to start, we'll walk you through some of the most important factors to consider when choosing a new head unit.

A replacement head unit in a car. — Westend61 / Getty

Choosing a Head Unit: Important Factors

There are four primary factors that can affect the suitability of a head unit for use in any given car sound system. Depending on the specific situation, some of these factors will be more important than others.

Budget: When upgrading a car audio system, it's important to be realistic. Anyone can build a killer sound system by throwing enough money at the problem, but not everyone has that option. That's why it's important to think about what you want, consider the other components you may need to buy, and choose a head unit that fits your budget.
Power: This refers to the audio output that the head unit sends to your speakers. More power means louder sound and less distortion at medium and high volume levels, but connecting a powerful head unit to weak speakers won't provide great results.
Aesthetics: The way a head unit looks is going to be more important for some people than others. The head unit is often a centerpiece in the dash of a vehicle, so it's important to choose something that doesn't look ugly. In some cases, aesthetics may even lead you to leave the original head unit in place.
Features: The reason we use the term "head unit" instead of "car radio" is that a head unit can handle so much more than just basic radio duties. If a particular feature is important to you, like Bluetooth or MP3 compatibility, then make sure to focus on that.

Anyone who is working on a budget will want to find a head unit that meets or exceeds his or her needs in the other categories without breaking the bank. However, someone who is trying to build the perfect sound system one piece at a time will have different priorities. With that in mind, we'll take a more in-depth look at the different qualities that you should look for in a great head unit.

Form Factor: Single vs. Double DIN

Before the process of selecting a head unit can begin, it’s important to check out the dash of the vehicle it will be used in. Most head units fit into two size categories that are referred to as single DIN and double DIN, and most vehicles have either a single or double DIN dash receptacle.

If the existing head unit is about 2 inches (50mm) tall, the replacement needs to conform to the single DIN standard. If the existing unit is 4 inches (100mm) tall, then either a single or double DIN head unit can be used. However, a spacer is needed in order to install a single-DIN head unit into a double-DIN receptacle.

Check out our guide to finding the right size head unit for more information.

Aftermarket vs. Original Equipment

When you start thinking about the aesthetics of a head unit, one concern that a lot of people have is that an aftermarket head unit won't look right. While a properly installed car radio will look as clean and professional as the original radio, it's true that some aftermarket car radios just don't match with the rest of the dash.

Leaving the original equipment (OE) head unit in place typically isn’t the best idea, but it is an option if it's shaped strangely or you just want to stick with the OE look for aesthetic reasons.

If an OE head unit already has all of your other desired features, you may want to skip buying a new head unit altogether and just install a new amplifier and premium speakers. That typically won’t provide the best possible sound unless the OE head unit has preamp outputs, because that type of setup will typically result in some sound distortion.

If the original equipment head unit does have preamp outputs, or if the vehicle has a factory amp, leaving the OE head unit in place and installing a nice amp and speakers can work out just fine.

If you do want to upgrade the head unit, but you're worried about it not looking right when you're done, then pay special attention to what your options look like when turned on and turned off. You may also want to search for pictures of vehicles like yours to see what has worked for other people.

Audio Sources

The right head unit audio sources will depend on personal preference since everyone has a media library made up of differing amounts of cassettes, CDs, MP3s, and other digital music files.

Depending on what you have in your own collection, you may want to look for a head unit that can play:

Cassette tapes
Compact discs
DVDs
Blu-ray discs

While cassettes have been phased out of OE head units, some aftermarket double DIN head units can play both cassettes and CDs, and there are also head units that include CD changer controls.

Other units are capable of playing digital music files, including MP3, AAC, WMA, and others, that have been burned to CDs, and there are also in-dash CD changers that fit into the double-DIN form factor.

If your entire media library is digitized, then you might want to look for a mechless head unit. The term “mechless” indicates that there are no moving parts inside these head units. Since they are incapable of playing CDs or cassettes, you can play music from USB sticks, SD cards, or internal hard drives.

In addition to those options, head units typically include some type of radio tuner. Aside from the basic AM/FM radio that most head units offer, you might want to look for a head unit that includes an HD radio tuner or one that's compatible with satellite radio.

Head Unit Usability

A head unit that has great features and looks slick won’t necessarily be easy to use. Since the head unit is the command center that you’ll use to control your entire sound system on a daily basis, ease of use is vital.

This factor is easy to gloss over, but it’s also a leading cause of buyer’s remorse. Even if you’re buying a head unit online, it’s a good idea to look for a display model at a local store to try out the controls.

If you can find a display model, position yourself so that it's placed roughly where it would be when you're driving your car. Imagine you're driving, and glance over. How easy is it to see the display and controls? Reach over, and try to operate the controls. How easy is it to find and use the controls without looking?

Head units with a lot of small buttons, or displays that are difficult to read, might look good, and have all the right features, but the overall experience is unlikely to be satisfying.

Head Unit Power

For audiophiles, power is one of the most important factors in the process of constructing a car audio system. However, it’s typically the power of the amplifier that gets people excited. Good sound systems bypass the built-in head unit amp with RCA line outputs.

There are two reasons to consider head unit power. If you’re building a car audio system on a budget, and getting the best possible sound isn’t that important to you, then it’s important to find a head unit that has sufficient power output.

It’s also possible to build a car audio system piecemeal, in which case you’ll want to find a head unit that has a good built-in amp and RCA line outputs. That will allow you to enjoy good sound right off the bat, and you’ll still be able to drop a good amplifier into the mix later on.

The way to determine the power of a built-in amp is to look at the RMS value. RMS refers to root-mean-square, and this number is actually meaningful in a way that advertising terms like “peak power” and “music power” are not. However, head units typically aren’t capable of outputting the full RMS value across all four speaker channels at once. It also takes more power to produce bass than other frequencies, so you can typically expect some distortion unless you use a high pass crossover.

Additional Features

Depending on the audio system that you’re trying to build, there are a number of other features to look for. Some of these are vital to the future expansion of the system, like preamp outputs, and others will be immediately useful.