The 12v power adapter by Jameco is a linear regulated power supply, which provides clean power, not the common switching adapter that is much noisier. Its wires have been spliced and re-attached to switch the polarity, in order to accommodate the amp's native Japan polarity. Do NOT use a non-Japanese 12v adapter with this amp, unless this modification has been made, else it will damage the amp. Original box not available. Shipping is included in price.