OSD Audio's SMP500DSP Class D subwoofer amplifier is designed for use with higher wattage passive subwoofers such as in-wall subs that require external power. It is rack mountable and 1U chassis. This sturdy sub amplifier is not for the faint of heart. It serves up 1000 watts of power peak and 400W RMS @ 4 ohms, so to say that it is powerful is an understatement. This sub amp does more than just supply power. You'll notice an improvement in the overall sound quality of your entire home theater surround sound system.