THD Electronics HP8 Hot Plate Power Attenuator, 16 Ohm The best-sounding and best-selling power attenuator in the world. Every component is selected and optomized for a 16 ohm load to always show the amplifier a 16 ohm load, regardless of the setting. Hand-built in the USA. The industry standard attenuator. Ideal for any amp driving a 16 ohm load, such as a typical 4x12 half-stack or AC-30.