I really think that a representative from RME should reply to this issue. I will not be using a Fireface UC and have in fact returned it to the store for a refund as the hum rendered it totally unusable. I tried it at different locations and at different people's houses and the hum came and went at different locations. What I suspect is going on is that there is some interferance of some sort. I think normally such noise would be flushed out of the system through a ground, however, the Fireface UC does not have a ground. I suspect this is a typical problem of such similar units that do not have a ground connection. I will therefore refrain from using such equipment in the future as it is totally unreliable in terms of background interferance. Make sure to use equipment with proper grounding - a 3 pin connection not a transformer pin. Maybe I'm wrong... but then again I think an RME expert should also express his view.

The fact that the device worked at certain location and didnt work at another seems to me some sort of electrical interferance... the mic and cables used during my test were identical so its excluded that the cable or the mic was faulty. When I touched the top of the fireface or the metal part of the xlr cable the hum was reduced... I think I was actually earthing the device and removing the noise... same thing that happens with ungrounded guitar amplifiers... its fairly common... thats why a ground is always a useful feature.

Hi,
I have the same issues and tried almost everything. Is there any possibility to connect a proper power supply with grounding?