OWI 2X2AMPGRN1S61 is a self powered speaker/amplifier (AMP1SGRN) on a 2x2 metal tile and backcan assembly. It is UL Listed, Energy Verified and Energy Star audio product. This unit can drive up to four speakers connected series parallel to have a net impedance of 8 ohms. With an included UL Listed, Level 5 (Energy Star), 15V, 3.5A power supply, the amplifier can output 32 or 8W per speaker in a four speaker hook-up.