First of all, not everyone likes Audyssey (though I do). Secondly, this tech is NOT a substitute for everything else involved in creating a good acoustical space. I think of it as icing on the cake.
Then, I've read an acoustician's post where he said if he tried to design the absolute worst acoustical space he could imagine, it would pretty much look exactly like a car interior.
Now, I do know a couple of folks who spend more on their car audio than in their home, because they actually spend more waking hours in their car. Still, YMMV, and a miracle is the last thing I would expect . . .
btw the 606 uses 2eq, iirc, and multEQ XT is two steps above that (best consumer version).