I second the Marchand line of products. I have the xm126 tube xover. It was first used with 3.6's for active bi-amping. Now I use it with my ML CLS's and ML Depth sub. They may not be pretty, but they are built to perform. Try to go tubed if at all possible. Watch for monthly specials. If you are up for "DIY", they offer several levels of kits. Every now and then, they come up for sale on Audiogon.
