Hey, I just recently tried plugging in my Washburn AB 32. I run it through a gk 1001rb and an avatar 4ohm cab. I'm getting huge feedback on regular, low volume settings. The soundhole is awkwardly shaped (like an oval), and the one rubber feedback buster insert i've tried didn't fit. I really want to be able to plug this bass in, but the feedback is atrocious. Please give me some suggestions. Thanks.