Hello,
Thanks for your post.
Please make sure to check with IK Multimedia technical support. They will be able to look into this for you. Send me a PM with your ticket # once your ticket is open.
Click here to contact supportPlease do note, if youre iRig HD 2 works with one iPhone, but not another using the same cable, and the issue is that there is no power or LED indicator. It sounds like you may need to go to the Apple App Store to have them check out your device.
Before doing so, I would check to make sure this is not a connection issue with the following two steps.
1) Clean out the Lightning port on your device with compressed air or contact cleaner
2) Remove any protective casing