I'm an iPhone customer. I'm on the "upgrade every 2 years" plan with phones. I've been pretty happy with my iPhone 6+.
I have an iPhone 7 on order which should arrive later this week. You are probably aware that Apple removed the 3.5mm TRRS jack used for audio accessories starting with iPhone 7. Instead, they offer Bluetooth for wireless audio input and output or the proprietary lightning connector for wired audio input and output.
The first question that came to my mind was, "Ok, does that mean that the lightning connector feeds a digital signal or can it send an analogue audio signal? Is there still an digital to analogue converter in the iPhone? Or are the separate headphones, speakers, or microphones responsible for conversion from now on?"
Why does it matter which device does the conversion?
Digital to analogue and analogue to digital conversion is easy to do but it is difficult to do really well. The iPhone's converters have historically been quite good for a consumer device.
For wireless audio, the iPhone will, of course, send a digital signal. So any wireless audio devices will need to do the analogue to digital or digital to analogue conversion (A/D D/A) themselves, always communicating back to the phone with a digital signal.
But what about devices connected to the Lightning connector? I suspect that the Lightning port can actually provide an analogue audio signal and that the iPhone 7 still has an A/D D/A converter. I assume this because the little adapter Apple includes with the phone and will sell separately is priced at $9.99 USD. This likely means that it does not include a converter. It would likely be impossible for Apple to sell the adapter at that price if it did. And I expect that if it did include a converter, Apple would want more than the entry level, lower quality converters it would have to use to keep the costs down low enough to sell the dongle for $9.99.
Hopefully I'm right because I have two devices for which I rely on the iPhone: Tentacle Sync timecode clock and the RODE VideoMic Me.