Memphis Audio Mxa850.5M Water Resistant 5 Channel Amplifier - Memphis Xtreme Series Memphis Xtreme Audio amplifiers are water and element resistant and designed for use in the harshest conditions. Whether you need the power to kick sound from a wake tower or want to keep the party going at the dunes, these amplifiers are engineered to withstand anything you throw at them. This Mxa850.5M is a 5-channel amplifier that features marine-grade construction and pumps out 850 watts Rms. It also features variable subsonic filters and bass boost to give you the maximum amount of control. See below for more features and specifications.