Thank you, Richidoo. This is pretty fancy stuff. I just have a pair of the "entry level" MK Xs. I was wondering if anyone knows anything about them and/or has any opinion about them. I use mine as main speakers. I've kept them since my old days at Soundhaus in the early 70s. They originally belonged to Mike Kelly who modified the crossovers when he was at Duke (before he went to ADS/Braun). I've thought about changing them out if I can find a pair of ADS l910s, but I'm not sure if it would be a significant improvement. Thank you again for your reply and for your interest.