ART Pro Channel II Microphone Preamp/Compressor/EQ Professional Tube Based Selectable VU Metering Professional Tube-Based Microphone/Line Recording Channel. Three independent World-Class modules: tube mic pre, switchable optical/tube compressor, and tube EQ Warm, Smooth, and Silky Sound Quality. Precision Detented Potentiometers. Selectable VU Metering (mic pre out, compressor out, or Main Out).