Recently picked up a fireface 400. Works great unless I choose preset 3 (hurry, click preset 8!)  Also on compter reboot, my monitors feedback something awful (just like with preset 3) until The RME Mixer software restarts. 

The set up is with Mac mini Server.  Firewire 800 into a hardrive FW 400 between the hard drive and fireface. 

I have an FMR RNC on ins and outs 5 & 6.   Per FMR suggection, I am using a traditional TRS - Dual TS (Insert Cable) cable for the connection.

So Output 5  has a TS that feeds the Tip of the TRS and the sleeve of the TRS feeds a TS inserted into Input 5  .  Same goes for Out 6 and In 6 as the FMR RNC is dual channel. 

The only way to bypass the feedback is to unplug the RNC. 

I can avoid clicking preset 3, but I cant avoid computer restarts forever.