hi there! i have a problem with my new amp head...crate gt-3500h shockwave..it says to have an fx-loop...well i see a line in/out that it was supposed to work as an fx-loop...as i read to manual these jacks have double duties...line in bypasses the preamp stage of the head and the line out is for post eq...both combined should work as an fx-loop i guess...but i dont see that...when i plug my boss ns-2 i can only hear a clean sound (the amp bypassed its preamp stage)...i wonder if the problem remains and with rack effect units...any ideas to make things happen? thx!