you should make sure the Orville is the cause of the noise. Disconnect every other piece of gear and listen to Orville >Speakers only. Keep your levels DOWN!!!!
If Orville is making that noise, you can try resetting the unit, even though this sounds like a mayor problem. Resetting requires powering the unit while holding down the 8 key. THIS WILL ERASE ALL YOUR PRESETS!!! So back them up first.
If the problem is still there, you should contact our german distributor Sound Service in Berlin or firstname.lastname@example.org for servicing the unit.