After updating to iOS 10.3.1, a number of Apple users have noticed that DACs such as the Chord Mojo can no longer connect to their iPhones or iPads.
One user on Apple's Discussions forum claims that since the upgrade, they cannot connect from iPhone 6 Plus to a Chord Mojo DAC/amp.
"After upgrading the phone, the digital output drops completely after a few minutes and I need to unplug and restart the app," says the user named 'RB64'. On the same thread, 'WillVR' says he has had a similar issue with the FiiO E17K DAC.
Users on the subreddit r/Headphones have noticed an issue with Apple's own lightning-to-USB camera adapter too. Posts on that forum indicate several people have received a pop-up message saying "This device is not supported".
When asked about the issue, Chord Electronics gave this response:
"Apple has recently released the iOS 10.3 software update for the iPad, iPhone and iPod and this has affected the operation of some accessories, including the lightning-to-USB adapter cable (Camera Connection Kit). This is causing issues where the audio will not play on the connected product, but the track will still show as playing on the Apple device. Apple has been made aware. Consequently, DAC/headphone products, including Mojo, may be affected. The current advice is to wait for the next release of the iOS 10 before updating".
Apple has yet to respond, but from comments sent to What Hi-Fi? it seems the upgrade included attempts to limit the usability of uncertified iPhone accessories, but has also blocked some Apple-certified devices too.
We would recommend anyone considering using a Chord Electronics or FiiO DAC with their iPhone refrain from updating their operating system until Apple has confirmed a patch.
If you have experienced issues using a DAC with your iPhone, please let us know in the comments.