I have CLS 2Z and use a Genesis Metal cone 12 sub with good results. I have also used an Audiopro B250 with good results but I felt the crossover slope with the b-250 was too gentle (it is 6db). As a result you have to have the CLS go down lower before getting out of them. With the Genesis I use a 24db Marchand crossover in between. It works very well.
