I am trying to use the ARC Advanced Room Correction System) package (for the first time) to measure my studio and to correct the coloration and am using a Fireface 800 with a Apple Mac core2duo laptop running OS 10.5.8.

The ARC system requires that the Direct Monitoring to be switched off. I can't seem to see how to do this.
I can hear the mike picking up the signal coming through the speakers and start to colour the sound as the levels increased to those outlined by the ARC manual.

I have the mic plugged into channel 7 as it requires phantom power.
The outputs to the Genelec speakers are connected to outputs 1 and 2 on the back.
As stipulated in the ARC manual the Fireface is set to 48 sample rate.

Looking at the RME mixer on my computer screen there is ?
one bank of faders to control inputs,
one bank of faders to control playback,
one bank of faders to control outputs.

I assumed that I had to just turn down the outputs and use the playback to monitor the sound as I am thinking this is what is coming from the software. But alas I always am hearing the room start to colour the sound when I get the levels up and any further up into the target areas it starts to feedback.

I don't think this is what is supposed to happen but I really don't know as I am a first time user of the ARC system and am new to the Fireface 800, mixing and measuring a calibrating rooms...

I hope that someone can help in this as I want to get the measurement right or I will really have a bad sound from my mixes!!

Thanks