I have the Def7001s, and the 2500def for the center, and def surround, with a total of 1500, plus 1500, plus 300 watts for the low range and did not think I needed to add a sub-woffer. After talking to Dave G. on this site I decided to try out a sub and they only had the Def super cube 2, I wanted to try out the super cube 1, But after hooking up the S.Cube 2, 1250watts of power, I bought the S.C. 2, It really added a new dynamic dimension, you really feel the floor rock when listening to music that calls for it! I am a Definitive speaker fan, and they are not cheap but worth every $$. I turned down the low range on the mains to see the difference the sub made and to get more highs and mids out of the mains. It worked and I could not tell where the bass was coming from, what a sound and I just bought a Onkyo 875 and not hooked up yet to see how they will sound, right now I have my Denon2805, 100 watts PC A/V Receiver. Hope this was helpfull! Have a good Christmas!!