Ultimate Car Audio by JBL.JBL Concert Class AB Power Amplifiers are available in 2-Channel and 4-Channel models to bring superior and serious features with competitive price point. Both models have compact and elegant footprint, which are equipped with Adjustable High-Pass/Low-Pass Crossover Filter, Auto Turn on Facility, More importantly, they have reliable performance. 2-Channel amplifier can deliver 65 watts RMS of detail-enhancing musical power. If you only want power the bass, bridge the 2-Channel to 170 watt RMS. 4-Channel models will send 70 watts RMS to each of your front and rear speakers, the bridge model can power a pair of subwoofers with up to 180 watts RMS each.