Howdy y'all, I use a Shadow SH-RB-Pro pickup on my bass, then into an HPF-Pre, and finally, my amp is an Ampeg BA115HP. I can't turn it up all the way without getting that horrendous low-end, rumbly feedback. The Shadow is equipped with settings that are "cheat codes" in a sense (as Colin from The Brains puts it on his YouTube channel), which are very helpful, but don't quite get the job done. I also got the HPF-Pre low cut/high pass filter for battling feedback after seeing it on the Discover Double Bass YouTube channel. I've considered adding a second soundpost, but I'm hesitant since I play acoustically a lot. I'm also not as big a fan of tape or foam blocking the f-holes, only because I'm not a huge fan of the look. I've talked quite a bit through Instagram with Gollo Garcia from The Delta Bombers, and he suggested an EQ pedal where I can cut out/add highs/lows. I've wondered how the heck Jimbo from RHH doesn't seem to have feedback problems, but I think a lot of it has to do with the way Jason Burns builds the Blast Cult basses. Any help/advice/tips would be greatly appreciated. Thanks so much. ---Will V.