I just bought a Hartke Kickback15 off ebay and brought it home. Wow, it's VERY bright sounding!!! Also, I'm not sure how to effectively use the shape control. I would benefit from comments you guys may want to offer up - if you're using a kickback and have certain settings you prefer, please respond. By the way, I play both Reverend Rumblefishes and vintage Jazz basses. Many thanks!