I'm confused a bit about how the Preamps in my K3s work. When Preamp2 is engaged are the preamps stacked for a total of 30db additional gain or does the Preamp2 engagement disengage Preamp1 for a total of 20dB? Or perhaps they are both engaged for a total of 20db with Pre2 boosting over Pre1 by 10db? 73 jim ab3cv