Front firing design Single slot port for optimized bass output Front mounted volume control Built in 400-Watt Class 'A/B' high efficiency power amplifier 12dB/Octave variable filter from 40 Hz to 180 Hz 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