Focal Impulse 4.320 Amp Compact Digital 4 Channel Amplifier Class D 4x55w RMSFocal Impulse 4. 320 Compact 4 channel amplifier 55 watts RMS x 4 Big power from a tiny amp Focal designed their Impulse 4. 320 4 channel amplifier to fit almost anywhere inside a vehicle. The Impulse 4. 320 sends 55 watts RMS to each of your speakers from a chassis that's smaller than a brick. You can also use an Impulse 4. 320 in 3 channel mode to power a pair of speakers with 55 watts RMS each while sending up to 160 watts to a sub. Plays well with