Interesting I just got a Quattro last night and was coming here to post that, from a leak data perspective, it was the worst night since going on CPAP back in May. I seem to recall someone talking in a related post about a fitting video to help figure out how to tweak your mask. I am presuming that you want it loose to allow the flap-thingies around the edge to inflate and form to your skin.
I was wondering, though, since I sleep in my recliner most of the time due to back issues if I shouldn't keep trying to wear the chinstrap to keep my jaw from relaxing too much once I go to sleep.
Paul ~ aka kasualkid