SF Grand Pianos/REL Storm III combo - help

Hello, everybody! This is my first post here on Audiogon and it's a troubled one. Recently I've been busy building a decent multichanel system. At the moment I have Sonus Faber surround speakers (Grand Pianos on the front), REL Storm 3 sub, McIntosh MHT 100 receiver, Sony xa9000es SACD player and Denon 2900 universal player. I'm trying to set up the sub for a few days and still can't reach even a satisfactory result. The bass is boomy, muddy and abstract. Given the fact the both the speakers and the sub are supposed to be great components I guess I'm doing something wrong. Anyone has any experience with Sonus Faber and REL? What's the correct set up (my room is about 50 square meters with the wooden floor and it somehows usualy causes boomy bass) or maybe you guys can come up with any ideas?