Infotainment Buyers Guide - Impact of Head Units on Car Audio Sound Quality

Improving car audio sound quality probably shouldn't start with a new head unit.

Your Spotify playlist begins the first few notes of your favorite song.

As the artist drops your favorite lyric—you wish it sounded better. You still love the song, but it didn't give you that same feeling it did when you hear it on a better sound system.

You decide time has come to upgrade our car audio.

This guide will help you make better buying decisions if you're in the market for a car audio upgrade.

Improving Your Car Audio - Head Units and Speakers and Amps, Oh My! Buyers Guide for Car Audio Head Units

If you're like most car audio accessory shoppers, you'll probably start searching for a new head unit first. Then you'll look for a set of speakers. If you've budgeted well, you might even consider an upgraded amp.

When all is said done, how sure are you, that the improvement in sound will be worth the investment of money and time?

To get what you expect from a car audio upgrade, consider multiple factors; format of your music collection, your personal musical genre preferences and compatibility with your vehicle.

A basic understanding of how digital sound works, will help you make more informed and better purchasing decisions.

A VERY Basic Primer About Digital Sound

Car Audio Upgrades and Head Units -A VERY Basic Primer About Digital Sound

Though we discuss digital sound as a relatively new technology, it has existed since the dawn of human existence.

Sound represents how our brains interpret oscillations in air pressure. Those oscillations in air pressure cause our eardrums to vibrate. Those vibrations go straight to the brain, where it determines the "sound" we hear.

The process just described, defines what digital sound actually means. Digital sound means converting oscillations in air pressure—analog sound—into electrical impulses that can be transmitted digitally using binary code.

Car audio functions using the same fundamental process.

Your head unit transmits sound digitally along speaker wire to an amp. That amp increases the strength of the digital signal and sends that to the speakers. The speaker then use that digital signal to convert the digital format back into a analog format that our ears can hear.

So if the end-game is to simply convert back to analog, why bother with going digital in the first place?

Digitally Formatted Sound Quality Remains Consistent. Analog Formatted Sound Degrades.

Car Audio Upgrades and Head Units - Analog Sound Quality over time

The benefits of digital come from the ability to maintain sound quality throughout the replication process. With analog formats such as cassettes and vinyl LPs, the physical makeup of the medium used to record the sound deteriorates.

A vinyl LP uses varying depths in the grooves on the record to record variations in sound. Over time, those grooves will change in depth and accuracy. Thus the quality of sound from the record will be poor.

With digital sound, no physical medium exists. The sound has been recorded in simple digital bytes in the form of one's and zero's. Those pattern of one's and zero's can be replicated without any change to the pattern.

As a result, digital sound quality never degrades. Unless of course you scratch your CD.

Ok, so what does all this mean in terms of what equipment I need to buy?

Digital Sound Relies on Quality of the Digital Data - One's and Zero's Never Change

If you're head unit only sends digital messages, how much does it impact sound quality?

Head units have virtually no impact on your sound quality—unless you're utilizing physical medium such as cassettes. In fact, read the descriptions for most head units and you quickly realize it's not about sound.

Look for a new head unit if you want added functionality such as a DVD player, an Aux input or a larger touchscreen. Buying a head unit only for the purposes of improving sound quality will leave you disappointed.

Really Want Better Car Audio? Start With the Speakers and Work Back to the Head Unit

Car Audio Upgrades and Head Units - Selecting the right speakers

Your car's speakers will make the biggest difference in your sound quality. Speakers have the most important role in the quality of your sound. Remember, the speakers will convert your digital music into a series of analog air pressure oscillations we call sound.

The fidelity of your speakers—specifically their range in terms of sound frequency—will provide the bulk of your sound quality.

Read this post about buying car speakers from the folks at Speaker Champion for good advice.

Digital Car Audio—Quality of Digital Music Starts With The Digital File

With all the talk about car audio components, we would be remiss if we do not mention the quality of the actual music file itself.

Sound quality begins with the digital file being played. 

How your analog sound gets digitized will impact your sound quality more than anything else, either good or bad. A poorly recorded or digitized sound file will produce poor audio irrespective of the quality of the hardware.

Remember that the benefits of digital sound have little to do with fidelity and more with quality of replications and the ability to maintain the same exact sound quality over any period of time.

Car Audio and Head Units - An Analog Sound Wave Graphed

Car Audio Upgrades and Head Units - Digital Sound Wave Graphed

Digital audio, the same process we use as humans to interpret analog sound, has imperfections. It can't exactly replicate analog sound.

An analog sound wave when graphed looks like a smooth curve. An unprocessed digital sound wave would not have this smooth curve. It would look more like a set of steps in the same general curve pattern as the analog sound curve.


Digital audio only records samples of sound at set frequencies. An audio digital converter (ADC) essentially interpolates what goes in between each sample. It fills in the missing data between each sample.

How often an analog sound gets sampled is called the sample rate. The higher the sample rate, the better the sound quality. The ADC has less empty space to fill in.

Another factor will be how much data gets stored every time the analog sound gets sampled. The more data stored for each sample provides more data for the ADC to fill in the small time frames lacking data.

As such, the higher the bit rate, the better sound quality.

CD quality sound usually has a sample rate of 44.1 kHz and a 16-bit depth.

You can create sound files with higher sample rates and bit depth, but unless the original recording utilized these higher standards, you won't get any better quality sound.

Music files that you download from online stores use the standard 44.1kHz sample rate and a 16-bit depth.

I Still Think I Need a New Head Unit…

Now that you better understand your car audio system, consider if really you need a new head unit.

If that's the case, start here with our Aftermarket Head Units: An Insider's Buying Guide. This informative guide provides the questions you need to ask—and the answers you need to look for—in order to make a smart head unit purchase.