Published on Jul 26, 2019
So I figured the out the hard way, so I thought I'd post what I found.
The reason for the noise is because Apple thought they would be clever and combine the head phone jack with the ability to use it as a USB connector.
Here is the pinout of the headphone jack.
So if you try to play while charging, the USB will countinuiosly try to connect, adding noise to the right and left channels of the head phone jack.
So that's my theory, and killed the project I tried, making it an ambiant/nature sound generator. It may only apply for Generation 1 Shuffle.
So, I hate Apple