To make things even more complicated, I have a Sony Xperia Z2 which uses a 5 point jack plug TRRRS, as far as I know the extra connection is only used to receiv

To make things even more complicated, I have a Sony Xperia Z2 which uses a 5 point jack plug TRRRS, as far as I know the extra connection is only used to receive microphone signal from the included noise cancelling headphones.[1] (Since the noise cancelling logic is handled on the phone). [1] https://www.sonymobile.com/global-en/products/accessories/digital-noise-cancelling-headset-mdr-nc31em/ https://www.sonymobile.com/global-en/products/accessories/di...