Editorial: Headphone jack vs. USB audio. Which is better?

Ever since the first rumors that popped up late last year that Apple will be dropping the headphone jack from its next iPhone, the tech world has gone into a tizzy. Since then other manufacturers have added fuel to the fire, launching models without headphone jacks to preemptively attack the next iPhone and do the tech equivalent of the "First!!!" comment on YouTube.

By now you must have read a dozen thought pieces on how dropping the beloved analog headphone jack is a bad idea, and at the same time others have been writing about how the Lightning port (or USB Type-C on other devices) is the future for all our audio needs.

But before we throw our hat in either of those rings, it's important to assess both of them and see what advantages and disadvantages they offer. Not that it's going to change the course of what companies are planning to do and it certainly won't stop Apple from dropping the headphone jack from the next iPhone, if it so wishes, but as a consumer you should hopefully be more educated and when the time comes would vote with your dollar.

Before we start with the pros and cons of either analog or digital audio output, we should learn a bit about how audio is processed on your phones. Like your computer, the modern smartphone has something called the audio codec IC, which is responsible for processing all the sounds on your smartphone. It includes a digital to analog converter (DAC), analog to digital converter (ADC) and an amplifier, among other things. Every audio that goes in or comes out of your phone passes through this little chip, which is separate from the main SoC and takes up a tiny footprint on your phone's motherboard (about a couple millimeters in either direction).

The DAC processes the sound that exits the phone, including music and phone calls. The amp amplifies the analog signal so it's audible through the loudspeaker, earpiece, or your headphones. The ADC processes the analog signal received by the mics on the phone. There is a ton of signal processing going on - things such as applying audio effects on your music to noise suppression during phone calls from signal received from multiple microphones, it all happen inside this one little chip.

The Qualcomm WCD9335 audio codec (in dark blue) on the Galaxy S7 edge. Image courtesy iFixit.

The majority of the phones on the market come with a single audio codec IC. Think of it as the onboard sound card on your computer. These are good enough quality for most users and they keep getting better every year. A lot of the phone manufacturers use Qualcomm audio codec, since it's more economical if the phone also uses a Qualcomm SoC but some also use Cirrus Logic (notably Apple), or Wolfson. These three are the most common suppliers of audio codecs on your phones, with Qualcomm being the preferred choice these days.

However, some companies go above and beyond with a higher quality component. Think of this as an aftermarket sound card for your PC. This audio codec resides alongside the standard part (so now there are two) and usually only handles music playback duties, with calls and other boring stuff still being handled by the standard chip. These chips usually boast a higher sample rate conversions and also include a more powerful amplifier that are better suited for higher bit-rate audio and high impedance headphones. Some companies go even further and include a separate amplifier for even more powerful output. The LG V10, the Lenovo Vibe X3, the ZTE Axon, and some of the HTC BoomSound phones are known to have an additional DAC/amp unit inside.

So this is how audio has been traditionally sent to your ears. The SoC will send the digital data to the audio codec, which would process it and convert it to an analog signal, which would then go to the amplifier, which would then send it through the headphone jack (or the speaker). Your headphones would then just have to intercept the amplified audio signal and use that to drive the voice coil, which then moves the drivers, which produces the sound.

But USB audio is different. In this case, the SoC sends the digital data straight out through the USB port (Lightning, microUSB, Type-C, what have you) and there is zero processing done on the device side. Of course, since neither your headphones (nor you) can process the digital signal, it has to be converted to analog at some point. This is why every device connected to the USB port for audio purposes has to have its own DAC/ADC built-in. It processes the digital signal, which otherwise would have to be done on the phone and then sends it to the amp, which also has to reside on the USB device, so it can power the speakers. These parts take power from phone port itself.

If you take the example of a USB Type-C headphone pair, such as the ones LeEco now sells with its new phones, the DAC/ADC and the amp are actually placed somewhere within the cable, usually near the USB port itself. On some headphones, it could be placed within the microphone module, or sometimes within the driver units. This is not a new practice and this is how Bluetooth headphones have always operated, as they too receive pure digital signal from the device and then have to process it. They even have the burden of dealing with the wireless signal and have extra circuitry for that.

So now we have the basics out of the way, let's look at each of our contenders.

Headphone jack

The standard 3.5mm TRS (or tip, ring, sleeve) jack has been around for decades now. The best thing about it is that it just works. You plug it in and that's it. You never have to worry about whether or not it is compatible because in most cases it is. Higher end audio equipment does use the larger 6.2mm jack but on phones and other portable devices it has always been 3.5mm. You also don't have to worry about whether it's right side up or not and can plug it in the dark in your sleep. There are few things as ubiquitous and user friendly as the standard TRS jack out there.

So then why are companies so eager to get rid of it? Well, at least when it comes to Apple, the company is known to phase out older standards in favor of new ones. Whether it was floppy disks back in the day or CD drives a few years ago, the company is known to be ahead of the curve when it comes to recognizing outgoing trends and fully embracing the future, with others following suit. Apple probably sees the headphone jack the same way. It is just another way of outputting sound now, seeing as how Lightning can do that too. And Apple could certainly use the extra space created inside by removing the jack for other things. I mean, this is the company that changed SIM card sizes two years in a row just to make them smaller and smaller.

Why other companies are doing it is anybody's guess. They could have the same reasons as Apple or, as I mentioned before, this could be an attempt to preemptively one-up Apple (I can guarantee you will see tweets from all these brands claiming how they were the first to bring you USB audio and how Apple is copying them when the iPhone 7 releases later this year). It's not like there is no precedent for that (See: Huawei rushing to put pressure sensitive display on its Mate S when Apple's pressure sensitive display rumors came out).

Either way, I don't see a lot of reasons for companies to drop the headphone jack right now. I see people from the Apple camp trying to use the floppy disk example to justify this move on Apple's part. However, with floppy disks (and CDs, for that matter) there was already a better solution on the horizon that people had started to move to and dropping the existing standard was the only way to get them to move faster. USB audio, as we will see, isn't necessarily better.

USB audio

I find it amusing that we see digital audio output from our phones as the future. If you look back a decade or so, the phones then all had digital connectors and the standard headphone jack was nowhere to be seen. Remember the Nokia Pop-Port? Or the Sony Ericsson FastPort? Good times.

But that didn't work now, did it? A few years later, we all ended up coming back to the gold standard that was the TRS jack. Even Apple when it launched the iPhone chose to go with a standard (albeit unnecessarily recessed) 3.5mm jack, even though it would have made way more sense back then to just send audio through the 30-pin connector as some companies were still doing it.

So then why now? I think there is a lot of buzz these days around the whole high resolution audio thing. Manufacturers claiming they can use the pure digital output of their phones' USB ports to send you uncompressed high quality sound. But this is nonsense.

As I mentioned before, your ears are not compatible with digital audio. Whether it's 16-bit or 32-bit, MP3 or FLAC, your ears just don't give a damn. We can only listen to the analog audio after it has been properly amplified. And whether the processing is done on the phone or within your headphones is moot.

You could have high quality 24-bit track on your phone. It could get processed first within the phone and then sent over an analog connector to your headphones. Or it could get sent directly as a digital signal to your headphones and then converted to analog and to your ears. At which point during the chain the conversion happens is irrelevant. So saying USB audio is better because it sends pure digital audio is marketing nonsense as at some point it does get converted to analog and the end result is the same.

Also, having the audio processed on your phone in most cases would be preferable. The audio codec used on your phone could be of significantly better quality than the one on your headphones. Even relatively cheaper phones could have a pretty decent Qualcomm codec whereas a cheap pair of USB headphones is likely to skimp out on the quality of the onboard DAC and amp, thereby directly affecting the sound that you hear.

We are also adding to the cost of the headphones themselves. Phones aren't going to be cheaper because they now have one jack less but the headphones surely will be more expensive, regardless of how they sound, simply because of the added engineering and the cost of materials that will go into making them. Why do you think Bluetooth headphones are still so expensive compared to their cheaper and better sounding wired counterparts?

If you don't want to purchase USB headphones, you will have the option to use an adapter. So now this $5 accessory is entirely responsible for the kind of sound you hear, as it will be in charge of processing it. You can imagine how well that will go.

Here's where it gets annoying though. What if you want to charge the phone while listening to music? Also, imagine in future you have an Android phone, an iPad and a laptop. You will now need three different headphones, or at least two different adapters. Good luck with that.

It's easy to dismiss some of these as teething issues and something that will get better with time. But as I mentioned before, it didn't get better with time the last time we had digital audio connectors and we had to fall back on the good ol' TRS jack. That is unlikely to happen now, though, which means several years of unnecessary suffering with multiple adapters, cables and what not. And in the end if this was all going to be worth it, it would still be fine. But we have seen that it's not and nobody has really offered a compelling reason to switch to USB audio yet.

The funny part is, we have had USB audio for a long time now. The iOS devices already output audio through Lightning connector. Android phones running Lollipop and above can output USB audio. Even older Android phones with a custom configuration could output audio through microUSB. We have had a so-called superior audio interface at our disposal for a few years now, and yet no one switched to it. We hardly have any earphones or headphones that connect directly to them. We don't because no one cares. Not even audiophiles as the advantages are just not worth it, because there are barely any.

And yet we will soon be forced to switch to the digital interface completely. As an audio and technology enthusiast, I look forward to playing with them. But as a consumer I find it baffling that companies are willing to take the choice away from you of using your existing headphones just to save some space inside so your next phone could be even more unnecessarily thin, or worse, just to one-up each other.

Wireless audio

Among all this kerfuffle we might finally see the rise of wireless headphones as the preferred choice among customers. Like I said before, there is no stopping the 'no-headphone-jack' train at this point. But you can always choose to use wireless headphones over USB audio.

The advantages this offer are actually tremendous. For one: no wire. It's just one of those things that you need to experience for some time to truly appreciate it. You think you can live with cables but once you use a pair of good quality Bluetooth headphones, the complete lack of cables is incredibly liberating and you never want to go back to cables.

They also work with pretty much everything now. Your phone or tablet, regardless of brand, your laptop, maybe even your MP3 player already supports Bluetooth. It's actually far more universal than you think, second only to the standard TRS jack.

As for the audio quality, I know it has been the reason most people avoid Bluetooth headphones, yet every pair that I have listened to in the past few years sounded absolutely great and they seem to still be getting better. With lossless codecs like aptX and LDAC you don't even have to worry about data loss anymore. And did I mention they are wireless?

All in all, to me this seems like the way to go in future, and I have a feeling companies will be pushing for this too (I bet there is going to be a major push for Beats wireless headphones from Apple following iPhone 7 launch). No, it probably won't sound as good as your audiophile set of wired headphones, but I'd rather live with good sound instead of great sound and not deal with the hassle of multiple cables and adapters. And I swear I mentioned they are wireless. I cannot stress the importance of that enough. I mean, it's 2016. We have wireless chargers now but we are still arguing which cable is better for transferring audio instead of using the free air around us.

That's pretty much it from my side. If you have comments or questions, leave them in the section below.