Hi guys, i am very stoked about my new sum2 but i ran into some unknowns while calibrating the levels. -First i noticed when i send in a perfect square wave it comes out scewed/slewed. i have learnt this could be caused by low pass filtering or ac coupling. would love to know for sure. -i now have calibrated each individual channel around 9v peak to peak so it doesnt come out clipped with gain and master out potentiometers opened fully. i noticed that channel 3 cant get upto that level and has minor distortion. what can i do to check/fix this section? -about the send channels... ive noticed my effects sometimes send back over 20v peak to peak levels. what would be an acceptable level to tune these to? -in general what would be a wise calibration procedure? opening gain and master fully/ halfway or something else entirely? thanks in andvance, yoeri