Even if you chose the wrong mains.
LOL!
I had a similar occurrence with Audyssey and the QS8's (a pretty high xover point). Weird.
So did you change them to 80 Hz? I vaguely remember reading it's OK to manually 'raise' x-overs, but that if you 'lower' them, Audessy does not control that range (like 80Hz - 150Hz on my back QS8's. Anyone confirm or contradict this?
Will you be using the Ceiling FMB for the QS8's? My inclination would be to use that method AND to angle them a bit.
No FMB's for my ceiling mount application. I want more space than the ceiling clearance FMB's allow (2" not tilted, 3-4" tilted). I am creating my own DIY brackets. I'll post photos when I get into making them. Are your backs tilted? Are your HT pics up on Axiom?
You have a good week end as well.
Cheers