Pioneer GM-5500T 2-Channel Bridgeable Amplifier Amplifiers send a cleaner current to your car speakers. In layman's terms, this means that your stereo gets cleaner sound and frequency, ensuring a higher sound quality overall. The GM-5500T packs an impressive wallop despite its small size, with 820-watt max power capability. It can run 125 watts x 2 at 4 ohms, 190 watts x 2 at 2 ohms, or 400 watts x 1 at 4 ohms - whichever best fits your system configuration. Built into the GM-5500T is a very smart crossover network. It works like a gateway, routing the big bass signals (80Hz or lower, at -12dB/octave) to the speaker that handles them best, filtering out higher-frequency signals to that speaker. The GM-5500T's speaker level inputs allow you to connect your OEM unit (or any unit that doesn't have the typical RCA-type inputs) without having to buy add-on adapters.