I've used this UFX and Totalmix for over ten years and have never had a problem but I just discovered that when I use any amount of Reverb or Echo on a track it results in eardrum bursting feedback. I've tried everything I can think of including switching USB cables, going through firewire instead of USB, resetting the entire mix, etc. and nothing seems to help. It's not a routing issue because all channels (even hidden ones) have their sends and receives set to zero and still when I simply activate either reverb or echo the feedback immediately kicks in. The FX IN meter reads zero and the FX OUT meter is almost pegged. If I lower the volume of the effect it will lower the feedback. 

I did have the UFX unit sent to the local RME support specialist to replace a failing power supply a few months ago. Haven't been recording much since I got it back so maybe something happened then.       

Anyone have any suggestions? The FX are simply unusable at this point.

Thanks in advance