Orion XTR500.4 XTR Series 500 Watts RMS 4-Channel Bridgeable Xtreme Amp Class AB Stereo High Performance Car Amplifier with FREE Alphasonik Earbuds RMS Watts @ 4 Ohms Stereo at 14.4V: 90 Watts x 4ch RMS Watts @ 2 Ohms Stereo at 14.4V: 125 Watts x 4ch RMS Watts @ 4 Ohms Bridge at 14.4V: 250 Watts x 2ch