I personally would like to compare the Green Mountain Audio Callisto to the Zu Druids. Has anyone done this? Both are first order crossovers. The Callisto I own has a cast marble cabinet that is dead quiet and the best I have heard. The Druids are more SET friendly, but I am curious about the cast aluminum tweeter as most are bright in my experience. The Callisto also has a lifetime warranty. Any information would be appreciated from those who have heard both.