Introduction
Word on the street is that the iPhone 7 will ditch the industry standard 3.5mm headphone jack in favour of a smaller 2mm connector or – gasp! – even drop the headphone jack entirely.
It’s an interesting theory to say the least, however this has led some music lovers to ask how they can expect to use their existing headphones with Apple’s new flagship phone.
It’s a valid question, especially considering that it’s possible to spend almost as much on a decent pair of headphones as the phone itself.
Thankfully help is at hand: there’s a growing collection of digital-to-analogue converters – or DACs – which are increasingly compatible with iPhones.
These devices work by plugging into the phone’s lightning port either via a supplied cable or by using one of Apple’s lightning-to-camera USB adaptors. Then all you need to do is plug the 3.5mm jack on your trusty pair of headphones into the other end of the DAC as normal.
The advantages of using an external DAC
But short of Apple taking away the standard 3.5mm jack is there any reason why you’d want to use a DAC?
The answer has a little to do with your personal audio preferences, and a lot to do with the type of headphones you use.
Let’s begin with the basics and start by describing exactly what a DAC does.
As its name suggests, a digital-to-analogue converter converts a signal from its digital source to the analogue audio waves your ears end up hearing. Unless you’re still rocking a classic collection of vinyl (or, even less likely, cassette tapes) the music you’re listening to on a daily basis is stored digitally in either an audio file or CD.
At some point between its source and your ears, this digital signal is going to have to become analogue. This means that literally any device that outputs audio will contain a DAC.
The first advantage of using an external DAC rather than the DAC that already exists in your device is simply that – most of the time – the performance you get out of an external system will be better than your phone’s internal one. Why? Your phone’s internal DAC may be lacking either for reasons of cost, or else a desire to keep the phone as compact as possible.
The second reason to shell out for an upgrade is the fact that some of the more premium headphones on the market are ‘high-impedance’ headphones, which require more power through the headphone jack on your music source in order to work properly. (Impedance, for the record, is measured in a unit called ohms, and less than 50 ohms is considered to be low-impedance.)
The general consensus is that the harder a pair of headphones is to drive, the better they will eventually sound when paired with the right equipment.
An external DAC helps with these headphones as it can work as a headphone amp to provide the extra power needed to drive a high-impedance pair of ‘phones.
Now that you know how the technology works, let’s talk about which devices you can get your hands on to amp up your audio.
Chord Mojo
More powerful amplifierSimple volume controls that can be accessed through a pocketNeeds to be charged before useBig and cumbersome
The Mojo is one of the larger DACs we’ve tested as a result of the onboard battery that needs to be charged before you can use it with your iPhone.
Having to charge an extra device – even if that charge lasts for 10 hours – before listening to music out and about is hardly ideal, but that’s the price you have to pay for the Mojo’s more power-hungry innards.
Thankfully the Mojo puts that power to good use, delivering a much rounder sound than the stock iPhone jack. Without the Mojo the treble and bass frequencies tend to take over, but introduce the external DAC into the mix and the mids are much more present and full.
The device’s size means it’s a bit cumbersome, and not exactly an inconspicuous accessory. I ended up carrying the Mojo in my front pocket (where I could easily access the device’s volume controls), with the USB cable leading to my phone in my back pocket.
This probably won’t be your ideal setup, and that might mean leaving the Mojo behind when you’re going out on the town. Using the device at work, where I’m able to leave both my phone and the DAC on the desk, is a lot more user-friendly.
Other features include a second headphone output and a cool lighting feature whereby the volume buttons change colour based on the quality of the music file being received.
Audioquest Dragonfly Red/Black
Very portableNo battery to chargeLacks nuance of more expensive rivalsSeverely reduces volume control
Audioquest basically invented the USB DAC with the original Dragonfly back in 2012, but until now the the device’s power demands limited its use to desktop use thanks to the iPhone’s 100mAh limit on power draw through its lightning port.
But Dragonfly’s latest devices, the Red and Black models, completely change that. By using an all-new USB microcontroller, Audioquest’s Dragonfly Red/Black’s DACs now consume closer to 25mA, and can now be used happily with any iOS device.
This makes the Dragonfly a pretty compelling iPhone DAC. With a total size smaller than most USB sticks the Dragonfly fits easily into a pocket alongside an iPhone.
So what’s the difference (other than color) between the two flavors? Dragonfly Red is the more premium offering. It contains a better DAC chip, and outputs 2.1 volts of power as opposed to the Black’s 1.2 volts. That mean the Red is a better choice for driving high-impedance headphones.
With my headphones plugged directly into my iPhone I was comfortable listening to music with the volume set halfway, but with the Red I could listen at just a quarter and with the Black this was strangely reduced to just one volume bar.
In effect this means that you have a lot less control over the listenable volumes – turning the Black up just one volume notch meant that music was too loud, and turning it down one muted the iPhone completely.
Both versions, however, added a good amount of heft to the bass without sacrificing the clarity of mid frequencies. A playthrough of Daft Punk’s Get Lucky didn’t shimmer in the same way without the DAC than with it.
Whether you’ll want to pay extra for the Red version depends entirely on how difficult your headphones are to drive. If you’re looking for a personal anecdote, with my standard portable cans I could barely tell the difference between the two DACs. But, when I switched to a more power-hungry set of over-ears, the Red delivered a much punchier bass.
Neither the Dragonfly Red or Black can match the refinedness of the Chord Mojo, but their budget price and much more practical form-factor make for a far better portable listening experience.
Arcam MusicBoost S
Convenient form factorWorks as a backup batteryMinimal benefit to sound
The Arcam MusicBoost S is the most practical portable DAC that I tested, as it’s built straight into an iPhone case. As such, it’s the only device that I’d consider using on a regular basis whilst out and about with my phone.
The downside is that the MusicBoost S is slightly limited by its form factor – it’s built for just two models of phone, the iPhone 6 and the iPhone 6S. Owners of the 6S Plus or the iPhone SE need not apply.
Like the Mojo, the MusicBoost is a power-hungry DAC that will need to be charged, but the added benefit is that it can use its extra battery life to power your phone as well as itself.
Arcam claims that the 1200mAh battery has the capacity to hold 120% of an iPhone’s charge, which could potentially be a lifesaver if you’re using the DAC to listen to music on a long flight.
Disappointingly, however, similar to the previous Arcam MusicBoost we tested, I found the MusicBoost made the smallest difference out of all the DACs. I really wanted to hear more of an impact, but the difference was only audible with a more demanding set of cans.
That said, the potential market for Arcam’s portable DAC is probably small, limited to those with a specific model of iPhone and a pair of high-end headphones that can benefit from more power.
The positive news here is that the device doesn’t suffer from the same volume issues as the Dragonfly – the volume slider has more freedom to move around before your portable music player becomes an ear canal-destroying rock show.
If you’re in the market for a battery pack and protective case, and dig the idea of an enhanced audio experience, the Arcam MusicBoost S might be the accessory you’ve been searching for.
Do you really need an external DAC?
Let’s revisit the question we posed at the beginning of this article: Do you really need an external DAC?
Well, if Apple decides to ditch the headphone jack entirely, that decision might be made for you. But, until that happens, the answer is, as always, a massive “it depends”.
It depends on the quality of the audio you listen to on your portable device. To get the most benefit you’ll need firstly to be someone that keeps all their audio in ALAC format on your iPhone, or pay for a hi-res streaming service such as Tidal or Deezer.
Secondly you’ll need to be using a decent pair of headphones (preferably high-impedance) for your listening. Since your average person doesn’t have an external DAC connected to their phone, these headphones tend to be meant for home listening and as such are often bulky, expensive and are rarely designed to look good out in public.
But, if you’re using regular impedance headphones to listen to MP3-quality files or streaming services such as Spotify, then the perceptible benefit will be minimal.
Not to mention the fact that going through a USB DAC can actually remove functionality from your headphones by preventing you from being able to use an inline remote or mic.
If you go for a DAC without its own volume controls you may also find that the amount of control you have over volume significantly decreases.
After testing a handful of these units myself, I can’t help but think that there might be a place for mobile USB DACs. That might be a plane flight, where you have a tray on which to lay out your bulky listening devices and where wearing a bulky pair of headphones is much less frowned upon, or out in the yard while you’re doing housework.
Where you likely won’t have a good time using a DAC is while listening to music on your commute in the morning … that is, unless you like carrying brick-shaped audio hardware with you wherever you go and looking like you just came from a ’90s music video.
Alternatively, the times when I most enjoyed using these devices was when at home, where I could relax wherever I wanted and lose myself in some music.
If you’re looking to improve your listening experience your money would be better spent on a decent pair of low-impedance portable headphones and some higher quality music sources.
If nothing else, though, this experiment has proved once again that audio is a very subjective world, and that you should never take someone else’s word without a pinch of salt. You might have different equipment at your disposal and you might be sensitive in ways that someone else simply isn’t.
So by all means give one of our suggestions a try, and let us know your findings in the comments below.
Source: techradar.com