Sony designed the Slim Series XM-4S amplifier for small vehicle installations, with a low profile that allows it to fit under most front seats. On the outside, the sleek inverted heat sink keeps vital internal components running cooler and lasting longer. Removable terminal covers keep all the wire connections protected and out of sight for a clean-looking installation. Underneath the hood, the XM-4S amplifier delivers 50 watts RMS to four 4-ohm speakers — plenty of power for even the most demanding speaker system. Or you can bridge your XM-4S into 3-channel mode, sending 50 watts RMS of power to two speakers while driving a subwoofer with 120 watts RMS from the rear channel. minimize