I received the used center speaker I ordered which I thought from the picture it was a C508 but it was actually a C50B. The mystery is solved since there is no C508 from Energy.
Yes I have the Take 5 Classic set which I got on a good deal. My room isn't large so they work pretty good but they don't get very loud. I did blow 2 fronts and so trying to find replacements or slight upgrades.