Anyone out there with a Servo 15? I own a used Servo 15 without the X-30. For my birthday, my buddy ordered me X-30 crossover box. The servo doesn't have any crossover or phase control settings, that's why he's getting me that. This is my first sub. I'm not sure if there's any use for the X-30. Can anyone here explain to me why we need it. I own a Marantz sr7200 receiver. I use the Marantz internal crossover. Although the menu doesn't allow me to set the crossover frequency, only the option of setting the speaker to small or large. Phase control?? What does that do?? ANy inputs appreciated. THanks!