I've never gotten a decent sound on acoustic with amplifi because you are only using the guitar speaker, not the high fidelity, as this us only used for effects. Here's my workaround. I use a preamp and an adapter to convert to mini, and plug into aux in. That's a pleasant sound, but all processing has to be done in preamp, mixer etc. I'm actually using a GP10 for preamp stuff, and have used acoustic and electric this way. Sounds great.