I've decided to add a couple of subwoofers to one of my 2-channel systems and wondered about the experiences others may have had with some of the subs I am considering. I am limited in floor space and would prefer a subwoofer taking up no more than 15" X 15" floorspace. So far, I am considering the Sunfire HRS series, Definitive Technology Supercube II, Elemental Designs A3S with 2 band parametric EQ, and one of the SV Sound cylinder subs. If I go with SV Sound, I will only be able to get one due to my space limitations. A Hi-Fi dealer that I have been dealing with for more than 30 years recommends the Definitive Technology. He uses Definitive Technology subs with his Magnepans in his personal 2-channel system and loves them. I am open to suggestions.