I'm building a cigar box amp, a Little Gem, as found here: http://runoffgroove.com/littlegem.html Now, I've got all the parts. I'm using a small 4-inch 8-ohm 8-watt speaker I salvaged out of an old set of RCA mini-speakers I had sitting around. What I'm wondering is if there's a way I could wire this so I had the option to use either a 9v battery or plug it into the wall via some kind of power brick. I've got a ton of power bricks around here and I know Radio Shack sells a variety of sizes of input jacks for them. Is this route even possible, and if it is, what kinds of extra components would I need to solder in to make it work? Would I need to wire in some form of switch mechanism to decide which power source would complete the circuit? Thanks!