Front firing design with small footprint Single slot front mounted port for optimized bass output (first generation has dual round ports) Built in 400-Watt Class 'A/B' high efficiency power amplifier 24dB/Octave variable filter from 40 Hz to 180 Hz Front mounted volume control Automatic signal detection circuitry Status LED indicators Low level (RCA) audio inputs Line through (RCA) audio outputs High level (high level) audio inputs Line through (high level) audio output 0 - 180° phase shift