Not sure if anyone else posted before, so I found the below links containing nice pics about what's inside the Apple adapter:
https://www.ifixit.com/News/apple-audio-adapter-teardown
https://www.deccanchronicle.com/tec...it-inside-the-lightening-to-35mm-adapter.html
Source: https://dc-cdn.s3-ap-southeast-1.am...q0tnu1bof8341gbcm6j3-20160921153239.Medi.jpeg
Source: https://d3nevzfk7ii3be.cloudfront.net/igi/XAaMDuwV63ilEhIx.medium
There's also an interesting test of more Apple audio dongles and "connectors" on https://www.heise.de/ct/artikel/iPh...apter-liefert-schlechteren-Sound-3325932.html, the table from in there where the iPad Air socket 106.7 dB (A-weighted) of dynamics for 24-bit audio files.
https://www.ifixit.com/News/apple-audio-adapter-teardown
https://www.deccanchronicle.com/tec...it-inside-the-lightening-to-35mm-adapter.html
Source: https://dc-cdn.s3-ap-southeast-1.am...q0tnu1bof8341gbcm6j3-20160921153239.Medi.jpeg
Source: https://d3nevzfk7ii3be.cloudfront.net/igi/XAaMDuwV63ilEhIx.medium