Ok, I did some fiddling around today and found some sizzle. But..........the 'booty' was now gone and I had to boost the volume a bit. Settings I started with were; Bass @ noon, Mid @ off, Mid Freq @ off, Treble maxed, Mid notch engaged (just don't like mids in my sound). I had to max the Bass knob. I had to boost the Gain & Volume and Master Volume to gain back some of the booty I was missing. I tried 3 different basses. The basses with Audere's in them don't seem to be a good match for the Shuttle. One bass has Barts and it sounded good and clean. I'm contemplating ditching the Audere's for something else. Maybe EMG's. One note though.....I had the amp hooked up to an Epifani PS112 instead of the GK's. I just didn't feel like pulling them out. Will do another test this weekend with the GK's.