Strangely Overloaded Bass with SF Concertos....

I have Sonus Faber Concertos (not the newer HOME model) which I power with my Classe CAP 151. This was a truly beautiful sounding setup.

Recently, we moved to a bigger house, and I got the chance to put the speakers on stands - instead of bookshelves.

I havenoticed that while they sound as beautiful and clean as ever on Jazz and Vocals, on rock, the Bass sounds tremendously overdriven if I give em even a little power.
I use a Classe CAP 151 - plenty of clean power, never even gets above 1/4 of its potential.

Could they be too close to rear wall? Don't know if it is my amp or speakers.... both are 2 years old, and hardly ever really taken out for a POWERFUL drive...
Yes, it is possible that they could be too close to the wall, or a corner. But if they were on bookshelves before, then they were pretty close to the wall then, too. Could be something else entirely.
What are the dimensions of the room? If anything the bass would be less out in the room versus on a shelf, unless there is a serious room mode.
Placement of speakers in the room is critical -- move them around, experiment. For some guidance, go to -- follow the link to "Room Placement" -- the exact formula offered may or may not work for you, but it's a good starting point.