Is there a way to control USB audio device settings from the iPad? It's possible to use the iPad as a USB host and connect up class-compliant USB audio interfaces through the Camera Connection Kit.

But is there a way to adjust their settings in iOS?  There is in OS X through the Audio/MIDI Setup:



The device's output level, for instance, is affected by the regular iPad volume controls, but the playthrough feature and input gain don't seem to have any controls, at least not in Garageband.   Is there a hidden setting somewhere or an app that can control such things?
iOS allows the currently frontmost app to control the audio session and to configure the audio input for its use.  So you would have to look in each app to see if it has any settings for audio while it is running.  

There is an API for an app to request an input sample rate.  However there currently appears to be no public API for an app to set the hardware audio input gain.