Just for the record, this is what I wrote to Apple feedback:
(If anyone really knows what the problem is, please let us know.)
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Apple iPad mini. Re: Hiss
Hi. I am one of the very unhappy people who can't use the iPad for recording since getting ios7. The apple forum is replete with stories like mine: ios6 recording was quiet - ios7 is noisy. I have tried every suggestion. Why won't anybody at apple tell us what the problem is? I have been using macs since 1986. All I want to do is record my songs on my iPad. Unfortunately for me, I recently brought my iPad-mini refurbished so there is no warranty. If I had bought it new I would be at the Genius Bar until I got the problem fixed. Did I mention how unhappy I am? Here are the specs: 1st gen iPad mini running ios7. Recording onto Multitrack DAW with a Samson Go mic to a 30-pin USB camera adapter, into an apple brand lightening adapter into iPad mini. Everything works fine except for the HISS.
Jeff