that is strange. I also have this Interface and everything is working fine. When you start a new project from scratch, does this also happen?
Where does the error 50 appear?
Which version are you using? (Check the about button please.)
What kind of iPad are you using?
Are you using the AD 480 Reverb via Interapp-Audio or via Audiobus with Auria?
Does this noise also appear when using the AD 480 Reverb stand alone?