Subject line covers it pretty well. This is KPA Solutions' excellent 25W power amp that mounts in the back of the toaster, using a little less than half the available space: http://www.kpa-solutions.com/camplifier/camplifier-studio/
Mine has barely been used, and ships with the appropriate US power supply and mounting screws. Loud, lightweight, and convenient. I'm only selling it because I sold my KPA. The price includes shipping anywhere in the continental USA - faster and cheaper than waiting for arrival from Germany.
Thanks!