Hi. Thanks for your replies.
Some more details:
I have tried clocking two devices from the Digiface - an Antelope Zen Tour and a Steinberg MR816X. I have the same issue on both. When I clock the Antelope and Steinberg with each other they appear to work perfectly. Both the other devices exhibit this issue on their outputs when I use the Digiface (NB - I'm not trying to run all three at once).
Im my Fireface USB Settings app I don't see any error count.
The sound is like an incredibly loud distorted version of the output sound - it's not white noise but more like a massively peaked version of my output. I terms of seeing it on the meters its hard to predict and hard to switch screen. I'm working in a venue right now and have had to take the Digiface out the system as it's obliterating the PA system, so will have to do further testing in my studio at quieter volumes.
An additional issue which is making testing harder is that the ADAT ports of the Digiface are really very questionable: they are so loose that some of my cables are literally falling out of them. I've measured the width of my ADAT cables with a digital caliber and they are totally within spec. Do you have any advice about this? Is it possible RME have switched components out because of the supply chain issues? It really isn't what I'd expect from RME.
I've checked my Fireface USB Settings app and always had strong sync.
I really want to use this product - I've used lots of RME in the past - but it doesn't really seem like it's up to par. Are there any other steps you'd advise before I return it?