The link below is a .cir file for MicroCap (demo version works fine). It is of the KG series amp Xo section. With it, you can toy around to see how you can tweak the boost and rumble filter. 1) download this file:KG circuit ..and rename it with a *.cir extention 2) download the demo verison of MicroCap evaluation versio 3)load the file 4)tweak if you want to (instructions on circuit for what to tweak) 5)Click Analysis,then AC,then Run. Do this and you should get a responce curve simulation Enjoy! if you have any problems, post here and I will try to help.