Not sure if this is a common problem, or if there is a common solution.
CHAIN: iPad OR iPhone (Air and 6+) to Belkin iPhone Charge Plus Lightning Rockstar to Audeze Cipher Cable and LCDi3
PROBLEM: Slight 60hz (and probably 120hz harmonic) hum, more on left channel, when plugged into power. Have swapped USB power cords, sides of the Belkin, and power worts. No change. IT GOES AWAY WHEN I TOUCH METAL CASING OF iPhone OR iPAD.
I have 2 Cipher cables, and have not tried swapping them. Do we think its a defective Belkin unit? I got that because it’s Apple certified enough that Apple sells them, could have paid less for alternatives.
Noise disappears if I do not have unit charging. I think my temp fix is to try one of my external batteries as charge rather than AC. This is more practical than super-gluing my fingers to iPad case each night.