Cool Running = Reliability: The 400RB-IV Series uses a  “dual rail power supply” that generates about half the heat of conventional amplifiers.  Low output signals run off a low voltage supply, and high level signals run off a high voltage supply.  This keeps the amp running a lot cooler and makes it much more reliable.  To cool the amp when its being driven hard, we’ve designed a temperature sensitive fan cooling system.  When the amp is under a light load, the fan is off or running at a low speed, reducing fan noise.  As the amp works harder, the fan speed increases to keep everything cool.

Takže pokud máš tuhle verzi RB-IV, tak při nízké zátěži má být vypnutý.