I ordered through HiFiForLess.com and they called me to see if I needed an 18V power supply. Nice touch. It just arrived & I'm looking forward to getting home to try it. Edit: I've only had a little time with the pedal and so haven't discovered all it can do. On 18V, it is quiet, warm, and smooooth like Andrew said. Even just kicking it in on Clean gives a nice fatness & boost. And I look forward to trying it on 9V.