Alpine R-A90S : 6ch Hi-Res Amplifier, 100W/75W x 4ch + 250W/150W x 2ch @ 2Ω/4Ω

R-Series 6-Channel Class-D Full-Range Hi-Resolution Automotive-Grade Amplifier, 75-Watts x 4-Channel + 150-Watt Mono @ 4-Ohms, or 100-Watts x 4-Channel + 250-Watt Mono @ 2-Ohms The R-A90S has a unique staggered power channel layout that has double the power on the last two channels. When looking to power a dual subwoofer configuration, the R-A90S’s 5th and 6th channels can be bridged to provide up to 500-watts at 4Ω. The R-A90S is matched in power and performance for the Dual 10-inch Alpine Halo S-Series Preloaded Subwoofer Enclosures with ProLink™. Thanks to the unique staggered power channel layout, the R-A90S can host different levels of power on each channel, compared to traditional, multi-channel amplifiers. This allows the R-A90S to grow with you as it can effectively function as both a 3-way active amplifier and a 5-channel amplifier by delivering the power you need to the channels where you need it the most.  Hear the subtle details you’ve been missing in your music. The R-A90S maintains an extremely low phase shift throughout the music spectrum, which minimizes audible imperfections in your music and allows your music to stay faithful to the original recording. With a hi-resolution frequency response, the R- A90S can reproduce sound with incredible accuracy that stays true to the artist’s intention. Using custom Alpine internal components originally launched in Alpine’s premium X-Series amplifiers, the R-A90S has dual post-filter feedback loops that correct signal distortion by making the output as close as possible to the original input for accurate sound reproduction. For the best possible sound experience, use the built-in bandpass, high pass, or low pass filter to individually power each component in your sound system and assign frequency bands for accurate and reliable sound reproduction. The R-A90S has input capability to add an optional RUX-KNOB.2 Remote Bass Control Knob (sold separately). The remote bass knob controls the bass in your subwoofer by adjusting the gain on your amplifier for quick bass adjustments when needed. Alpine’s R-Series line of speakers, subwoofers, and amplifiers have a heritage of sound quality that can be heard from a block away. The R-A90S is tuned to emphasize the characteristics of the R- Series speakers and subwoofers for a legendary R-Series experience. Features 6-Channel Amp with 5-Channel Power– With double the power on the last two channels, the R-A90S’s 5th and 6th channels can be bridged to provide up to 500-watts at 4Ω to a subwoofer system such as a pair of S-SB12Vs. An Amp that Grows with You – When you’re ready to upgrade your Alpine system, use the R-A90S to amplify a 3-way active system with enough mid-bass power to create the up-front bass impact you crave. Accurate Sound Reproduction – With incredibly low phase shift and hi-resolution frequency response, the R-A90S can reproduce sound with incredible accuracy that stays true to the artist’s intention.  Specifications Dimensions: 12.75" x 10.75" x 2" Hi-Resolution Audio Compliant (40k Hz)  Alpine’s Class D Amplifier Circuit  75W x 4 + 150W x 2 (4Ω, 14.4V, < 1% THD +N)  100W x 4 + 250W x 2 (2Ω, 14.4V, < 1% THD +N)  Bridged: 200W x 2 + 500W x 1 (4Ω, 14.4V, < 1% THD +N)  S/N > 85dB (ref. 1W into 4Ω)  THD + N < 0.03% (ref. 10W into 4Ω)  Frequency response: 10-45kHz (0/-3dB) Damping factor > 500 CTA-2006 Documentation Alpine R-A90S Manual