I recently purchased this amp. I can't get good tone out of it that the guy in the store was able to get out of it.

Anybody know any good Grunge-Punk settings?
there's an Ultimate Setting thread either in the Electric Gutiar forum or the GG&A forum... (too lazy to look myself, haha)

that should help you find some settings to try out. Like, maybe use the Kurt Cobain one, or something, and tweak it a litte and go from there?