The added amping of the second voice coil adds a nice tight depth to the sound. Surprisingly subtle at times, it obviously shows in bass-heavy material like hip/hop or dance. The ICBM unit works perfectly with an outboard amp to drive the second coils.
I would NOT recommend using the full-range Gallos in lieu of a subwoofer for HT, as suggested in the owner's manual. I've been testing various hook-ups with the new extended-version release of "LOTR--The Return of the King." You will still need an decent sub for the LFE effects. However running the Gallos full-range yielded a much-enhanced sound stage, and dynamic feel to the movie.
I've also replaced my rear surrounds with Gallo Dues which are a perfect match for the Ref 3s.
Ted