Work-pro WPA 4400 is an apt choice for a wide range of applications, thanks to its excellent audio quality even at high volume levels, and exceptionally rugged construction that ensures long life and durability. It provides a total of 4 stereo headphone amplifiers and 3 headphone output per channel, while the Main Outputs on the rear panel can be used to interlink any number of WPA 4400s for expanding your system.