Ok, so the problem is solved but in a strange way. Today i turned on my PC and found my Total Mix FX windows in a strange state. Both Windows were Multiface (1) and when i tried to activate it for the other Multiface it showed "disconnected". The breakout box had the host LED flashing even though it was properly connected.
I tried both HDSP Express cards but then it was shown as Digiface and in the settings dialogue under the disconnect checkbox it showed "detected". Rebooting and reinstalling the driver didn't help. I then disconnected it from power but that did not help either.
I turned of my Furman power conditioner and when i turned it back on and rebooted my PC everything was back to normal. I turned up the volume and found that also the irritating noise was gone, yay!

Still I need to find out what happened. The only thing i believe could have caused this is heat. Please take a look at the picture and tell me if my setup could cause overheating. There is plenty of space in the rack above, to the back and left and right. Only in the middle and below there is not. Do you think this is problematic and can cause the described issues?

Cheers, André

Try a different FireWire cable. Swap the Multifaces to see if the error follows. Swap the power supplies, they might be on the edge of failing.

If the problem continues after all the 'Digiface' unit or the card where it is connected to need servcie.

Could you make the file downloadable without the need for a Flash player?

Regards
Daniel Fuchs
RME