Hi, I have a vexing problem.
My setup is an ICM4+ with a 30 pin iconnectivity cable going into an apple (official, not knockoff) 30 pin to lightning adapter going into an iPad Air 2. I just want to send midi to the iPad, and have no use for the ICM4+'s audio passthrough functionality, so I've unchecked all the Mac/pc and iOS checkboxes in the audio info section and disabled all connections in the audio patchbay. MIDI sends to the iPad fine, but when it's plugged in via the headphone jack in this configuration there starts to be a loud digital noise. I'm wondering if this is a ground loop? I'm at a loss, as I would expect the iPad's audio output to be completely isolated from it's power/midi input. I'm still able to pass the original audio through but it's mixed with this horrible noise. When I unplug the lightning connector/iconnectivity cable all the noise immediately clears away.
Here is a clip:
The first 18 seconds is the sound of the noise, then I unplugged it. At 1 minute is the sound of the iPad when unplugged. At 1:20 it's plugged in again and later you hear the iPad audio mix with the noise from the ICM4+.
Do you have any idea for fixing this?