i fix that problem, finally!
you need to open DJ Player with already connected controller to iOS device and also run any of both midi apps: Midi Monitor or MIDI Wrench (they are Free in AppStore).
while DJ Player is working in background (playing anything from a playlist) i turns different sliders in opened MIDI Wrench app. after that i switching back to DJ Player (both apps is running) and tried to press any buttons, faders and jog wheels which was switched automatically to usual functionality (fast response, etc...).
maybe its a core-audio bug in iOS program code from version 7.0.6 (when all this happens) till current 7.1, because autoswitch in midi settings wasn't a problem for my VCI-400 until that.
all i can say about that is: you need to do that thing each time when you wanna spin in DJ Player because if both apps (DJ Player and MIDI Wrench) will be closed and removed from iOS taskbar - all midi settings will be cancelled.
by the way: just tested VCI-400 midi learn function in algoriddim djay2 on iPhone 5. mapping works fine but djay2 app has the same midi response issue as in DJ Player. problem is resolved in the same way as i described above.
Bookmarks