Since the moment I installed the RME Fireface 400 software I was horrified by the Icons that RME provided with the original software. Take a look here:
So I've looked around and found this trade on LogicProHelp forums. There some guy name s0niccurve made a new set of icons with photoshop. The set is great but I didn't like the fact that it wasn't rounded on the corners, so I reshape the icons to be rounder.it's much better now . Anyway, I saved the files in a icns format so it will be easer for many user to change the icons.
So, to replace to old ugly icons, right click on the Fireface Mixer.app and click on "Show package content". There, under Contents -> Resources replace the existing icns file ("mixicon.icns") with the file on the zip file.
Do the same for Fireface Settings.app
Download link: http://bit.ly/c3EG1c
Thanks for the original uploader!