Absolutely, the speakers without ARC2 sound 'louder', definitely. but not twice as loud. But more importantly, the mid's and high just came alive, and the effect of the sound stage as they like to say, whatever that is, had some meaning finally. I could hear instruments in places I had not heard them before.
I have on occasion switched the ARC2 back on just to play and each time I do it, I feel like I just threw water on things.
Perhaps ARC is going to work great on more conventional rooms, ones which are rectangular as in most homes, but I have been dealing with a real odd ball room with multiple materials in the construction which make each wall different and I am sure this plays into this. Maybe the software engineer who wrote ARC configured it for a standard type of room? There is a lot to this stuff.