Is this going to be running on batteries or AC? If AC, I would suggest using a LM1875 circuit, we have a guy on here that could set you up with the PCBs/components for cheap. I have a LM1875 amp and it's very clean, very good sounding. I haven't used it on an acoustic, but I used it for an electric guitar, and I've also used it to play music from my computer on.