The rumours of the removal of the 3.5 mm headphone jack were well-founded, but as a consequence, the phone comes as standard with a small accessory known as a Lightning to 3.5mm Headphone Jack Adaptor that allows you to connect the famous Apple 'ear buds' or other stereo headphones. What we have here is in fact a DAC, because the audio is taken from the Lightning port in digital form, making this by far the smallest external DAC currently available!
This adaptor is also available as a standalone accessory (for less than €10!) which means that it can be used by any Apple smartphone or tablet that features a Lightning connector. We managed to ged hold of one to check out its audio reproduction capabilities, and to try to find out whether it is compatible with Hi-Res audio, as this kind of audio output has generally been limited to 16-bit/48kHz with previous Apple products.
The answer comes easy - it is indeed compatible, because it features a Cirrus Logic CS42L42 chip, a 24-bit codec that supports 24-bit audio up to 192kHZ with low power consumption, combined with an integrated headphone amplifier that boasts an output of 2×35mW at 30Ω. You can even get a kit from Cirrus Logic, a rapid development platform for Lightning® connected digital headsets, and part of the MFi programme (Made for iPhone/iPod/iPad).
It's worth noting that a codec is essential because of the clear need for the digital signal to be converted to analogue in order to reproduce the iPhone's audio output, and also for analogue audio to be converted to digital in order to use the adaptor with a microphone-equipped headset.
When listening to some classical music pieces, we didn't manage to achieve high volumes using our Oppo PM-3 headphones: the output lacked power, which limited our listening pleasure somewhat, and it wasn't necessarily favourable to our initial impressions of the sound quality.
However, when playing back the tracks How to Fall in Love and Haunted House from the Bee Gees' Size isn't Everything album at a higher volume, we were able to confirm that the sound quality provided by the integrated DAC is on a par with some very good DACs, allowing us to listen to details throughout the audible range with real clarity; in fact, everything that makes listening to music enjoyable, which is not so surprising when you realise that the codec chip comes from Cirrus Logic.
As the converter chip is compatible with 24-bit audio at 192kHZ, it is therefore possible to stream Qobuz in Hi-Res mode (if you have the Sublime subscription and you've bought the albums), certain in the knowledge that files up to 24-bit/192kHZ will be decoded properly.
To satisfy ourselves fully, we listened to the start of the First Movement of Gustav Mahler's Symphony No. 5 by the San Francisco Symphony Orchestra conducted by Michael Tilson Thomas, as we know that the Hi-Res version (24-bit/96kHZ) offers a more dynamic sound than the 16-bit version at 44.1kHZ.
Effectively, the difference in dynamics is clearly perceptible, which is evidence that Qobuz Hi-Res digital audio files are decoded by Apple's Lightning to headphone jack adaptor.
This Lightning to 3.5mm headphone jack adaptor is therefore an interesting alternative to compatible DACs (including some that we haven't tested) for Apple smartphones and tablets, being so inexpensive and ridiculously small. It provides an uncomplicated way to connect to high-end headphones.
It's also good news for anyone who has or who might want to get an iPhone 7, as they'll be able to use it with the Qobuz app in Hi-Res mode, as well as for owners of older iPhones or tablets, who simply need to equip themselves with a Lightning connector (although this compatibility also requires an iOS update for your hardware)!
We conclude by returning to the kit available from Cirrus Logic that we mentioned at the start of the article, which features existing models including the Brightech MFi Pure Lightning Headphones, the Philips Fidelio M2L/27 and the Audeze El-8 Titanium. They offer a range of headphones featuring MFi_approved electronics, and thus equipped with a Cirrus Logic codec chip which is identical to the one used in the Lightning to headphone jack adaptor.
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