In the iPhone Ightning headset, it is integrated with DA decoding and ear amplifier chip, that is, we often say C100 chip.
The digital tail concept comes from the iPhone, when the iPhone removed its old 30-pin port and replaced it with a lightning 8pin port, since then, the iPhone only supports digital audio output.
Its random lightning interface EarPods headphones, lightning cable, are integrated with a small DAC decoding chip and drive headphones chip, we call it \"digital tail\".