I'm using that chip for a similar project. The cleanest sound I was able to achieve was using the +15v side of a regulated bipolar supply (Rod Elliot's board). It sounded great, but the regulator got too hot to touch so I shut it down. Velleman makes a really cheap 1a regulated, adjustable supply that I'd like to try in the future, but for now I have 4X9v batteries in series/parallel for a bit more than 18v. It still breaks up too soon for my taste, but I put a 50k pot between the guitar and the input and that cleans it up at the expense of some volume. I'm using an 8 ohm, 8-inch Peavey speaker (I think I like my Radio Shack closeout/ceiling PA 8" better). No preamp, yet. Glad to see someone else using this chip/board; keep us posted.