sstumpf- The massive amp is putting out 120 watts per channel RMS, I am running those CK6's on 2 channels not bridged and a pair of JL12w3's with a Massive D3600, and let me tell you the stuff Bangs loud and clear, no distortion real smooth. I had never used them and took a chance, boy am I happy. I just bought the same amps to set up in my S-10 ext cab, I have 2 10" Alpine Type S already and was looking to see if I should get a different set of components for the front. At this point I am probably going to go with the Massives. Their amps are small and seem well crafted, I have been rocking the same set up without touching it for about 4 years, 2 trips to sturgis and not even a hiccup from the amps, I like my music pretty loud (not extreme) and I listen to all sorts of music, from heavy metal to rap to house music and it all sounds good.
Just wanted to give you an option if you cant Find brand new speakers in the price range you are looking for.